RESUMEN
Studies in the field of wound healing have utilized a variety of different housekeeping genes for reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis. However, nearly all of these studies assume that the selected normalization gene is stably expressed throughout the course of the repair process. The purpose of our current investigation was to identify the most stable housekeeping genes for studying gene expression in mouse wound healing using RT-qPCR. To identify which housekeeping genes are optimal for studying gene expression in wound healing, we examined all articles published in Wound Repair and Regeneration that cited RT-qPCR during the period of January/February 2008 until July/August 2009. We determined that ACTß, GAPDH, 18S, and ß2M were the most frequently used housekeeping genes in human, mouse, and pig studies. We also investigated nine commonly used housekeeping genes that are not generally used in wound healing models: GUS, TBP, RPLP2, ATP5B, SDHA, UBC, CANX, CYC1, and YWHAZ. We observed that wounded and unwounded tissues have contrasting housekeeping gene expression stability. The results demonstrate that commonly used housekeeping genes must be validated as accurate normalizing genes for each individual experimental condition.
Asunto(s)
Perfilación de la Expresión Génica , ARN/análisis , Reacción en Cadena de la Polimerasa de Transcriptasa Inversa/métodos , Piel/lesiones , Cicatrización de Heridas/genética , Heridas y Lesiones/genética , Actinas/biosíntesis , Actinas/genética , Animales , beta-Globulinas/biosíntesis , beta-Globulinas/genética , Modelos Animales de Enfermedad , Femenino , Expresión Génica , Estudios de Asociación Genética , Gliceraldehído-3-Fosfato Deshidrogenasa (NADP+)(Fosforilante)/biosíntesis , Gliceraldehído-3-Fosfato Deshidrogenasa (NADP+)(Fosforilante)/genética , Ratones , Ratones Endogámicos BALB C , ARN Ribosómico/biosíntesis , ARN Ribosómico/genética , Reproducibilidad de los Resultados , Ácidos Siálicos/biosíntesis , Ácidos Siálicos/genética , Piel/patología , Heridas y Lesiones/metabolismoRESUMEN
Developmental- and tissue-specific expression of globin genes is mediated by a few key elements within the proximal promoter of each gene. DNA-binding assays previously identified NF-Y, GATA-1, C/EBPbeta and C/EBPgamma as candidate regulators of beta-globin transcription via the CCAAT-box, a promoter element situated between CACC- and TATA-boxes. We have identified C/EBPdelta as an additional beta-globin CCAAT-box binding protein. In reporter assays, we show that C/EBPdelta can co-operate with EKLF, a CACC-box binding protein, to activate the beta-globin promoter, whereas C/EBPgamma inhibits the transcriptional activity of EKLF in this assay.
Asunto(s)
beta-Globulinas/biosíntesis , Proteínas de Unión al ADN/metabolismo , TATA Box/fisiología , Transcripción Genética/fisiología , Línea Celular , Expresión Génica/fisiología , Humanos , Unión Proteica/fisiologíaRESUMEN
We developed a novel inhibitor of thymidine phosphorylase (TP), 5-chloro-6-[1-(2-iminopyrrolidinyl) methyl] uracil hydrochloride (TPI), that is about 1000-fold more active than 6-amino-5-chlorouracil, one of the most potent TP inhibitors. TPI inhibited the high chemotactic motility and basement membrane invasion of KB/TP cells, a TP-positive clone transfected with Rous sarcoma virus (RSV)/TP, to the levels seen in KB/CV cells, a control clone transfected with RSV. In nude mice, oral administration of TPI suppressed not only macroscopic liver metastases of highly metastatic KB/TP cells but also the level of human beta-globin as a molecular marker of micrometastases in the livers of the mice. These findings demonstrate that TP plays a key role in the invasiveness and metastasis of TP-expressing solid tumors and suggest that TPI might be a novel antimetastatic agent for blood-borne metastasis.
Asunto(s)
Inhibidores Enzimáticos/farmacología , Neoplasias Hepáticas Experimentales/prevención & control , Neoplasias Hepáticas Experimentales/secundario , Pirrolidinas/farmacología , Timidina Fosforilasa/antagonistas & inhibidores , Uracilo/análogos & derivados , Uracilo/farmacología , Animales , Membrana Basal/efectos de los fármacos , Membrana Basal/patología , beta-Globulinas/biosíntesis , Biomarcadores de Tumor/biosíntesis , Movimiento Celular/efectos de los fármacos , Quimiotaxis/efectos de los fármacos , Inhibidores Enzimáticos/toxicidad , Humanos , Células KB , Neoplasias Hepáticas Experimentales/metabolismo , Masculino , Ratones , Ratones Endogámicos BALB C , Ratones Desnudos , Trasplante de Neoplasias , Pirrolidinas/toxicidad , Uracilo/toxicidadRESUMEN
Prostaglandin D synthetase [PGD-S, prostaglandin-H2 D-isomerase, (5Z, 13E)-(15S)-9alpha, 11 alpha-epidioxy-15-hyrdroxyprosta-5,13-dienoate D-isomerase, EC 5,3,99,2], an enzyme that catalyzes the formation of prostaglandin D2, was originally isolated from homogenates of rat brain and spleen and is known to be a membrane-bound enzyme. Subsequent immunohistochemical studies have shown that PGD-S is associated with neurons in the brain of immature rats, whereas in adult rats it is associated with oligodendrocytes. Several recent studies have shown that the beta-trace protein isolated from human cerebrospinal fluid (CSF), the second most abundant protein in human CSF after albumin, is equivalent to PGD-S. In this paper, we report the preparation of a monospecific polyclonal antibody against purified PGD-S isolated from human CSF and the establishment of a specific radioimmunoassay for this protein. Using this radioimmunoassay in conjunction with immunoblot analysis, PGD-S was detected in various biological fluids including serum, aqueous humor, and rete testis fluid. In addition, an antibody prepared against human PGD-S partially cross-reacted with the PGD-S in the rat and ram. Using a monospecific polyclonal antibody prepared against purified rat PGD-S isolated from rat CSF in conjunction with [35S]methionine incorporation and immunoprecipitation techniques, it was shown for the first time that PGD-S is actively synthesized and secreted by astrocytes cultured in vitro, suggesting the astrocyte is the cellular origin of PGD-S in the CSF. The identification of the astrocyte as the cellular origin of this unique enzyme will allow the use of an in vitro system to study its regulation.
Asunto(s)
Astrocitos/enzimología , beta-Globulinas/biosíntesis , Encéfalo/enzimología , Oxidorreductasas Intramoleculares , Isomerasas/biosíntesis , Envejecimiento , Secuencia de Aminoácidos , Animales , Anticuerpos , Humor Acuoso/metabolismo , beta-Globulinas/análisis , beta-Globulinas/líquido cefalorraquídeo , Unión Competitiva , Encéfalo/crecimiento & desarrollo , Encéfalo/metabolismo , Humanos , Immunoblotting , Isomerasas/análisis , Isomerasas/metabolismo , Lipocalinas , Masculino , Datos de Secuencia Molecular , Especificidad de Órganos , Péptidos/síntesis química , Péptidos/inmunología , Biosíntesis de Proteínas , Conejos , Radioinmunoensayo , Ratas , Reticulocitos , Esquizofrenia/líquido cefalorraquídeo , Testículo/metabolismoRESUMEN
The human beta-trace protein has been cloned and has been expressed for the first time in a mammalian host cell line. Stable BHK-21 cell lines exhibiting altered terminal sialylation properties were constructed by cotransfection of cells with the plasmids pMT-beta TP or pAB3-1 which contain the cDNAs encoding the human secretory glycoproteins beta-trace protein or antithrombin III and pABSial containing the human Golgi enzyme CMP-NeuAc:Gal(beta 1-4)GlcNAc-R alpha 2,6-sialyltransferase (ST6N) gene. The beta-trace protein was purified by immunoaffinity chromatography and N-linked oligosaccharides were subjected to carbohydrate structural analysis. The enzymically liberated oligosaccharides were found to consist of 90% of diantennary chains as is the case for natural beta-trace protein from human cerebrospinal fluid. About 90% of the total oligosaccharides were recovered in the monosialo and disialo fractions in a ratio of 1:5. The monosialylated oligosaccharides of beta-trace protein coexpressed with human ST6N were found to contain NeuAc in alpha 2,6- or alpha 2,3-linkage in the same ratio. From 1H-NMR analysis as well as calculations of peak areas obtained by HPLC, 60% of the molecules of the disialo fraction were found to contain NeuAc in both alpha 2,3- and alpha 2,6-linkage to Gal beta(1-4)GlcNAc-R, whereas 40% of the molecules of this fraction contained NeuAc in only alpha 2,3-linkage to Gal(beta 1-4)GlcNAc-R. The alpha 2,6-linked NeuAc was shown to be attached preferentially to the Gal(beta 1-4)GlcNAc(beta 1-2)Man(alpha 1-3) branch of the diantennary structure. Therefore the in vivo specificity of the newly introduced recombinant human ST6N observed in this study supports the previously reported in vitro branch specificity of the bovine colostrum ST6N activity. Furthermore, these studies demonstrate the suitability of genetically engineered mammalian host cell lines with novel glycosylation properties for the production of human-type glycosylated secretory recombinant polypeptides.
Asunto(s)
Glicoproteínas/biosíntesis , Oxidorreductasas Intramoleculares , Proteínas Recombinantes/biosíntesis , Sialiltransferasas/metabolismo , Animales , Antitrombina III/biosíntesis , Secuencia de Bases , beta-Globulinas/biosíntesis , beta-Globulinas/química , beta-Globulinas/metabolismo , Secuencia de Carbohidratos , Línea Celular , Clonación Molecular , Cricetinae , Glicoproteínas/química , Glicoproteínas/metabolismo , Humanos , Lipocalinas , Datos de Secuencia Molecular , Oligosacáridos/química , Oligosacáridos/aislamiento & purificación , Ingeniería de Proteínas , Proteínas Recombinantes/química , Proteínas Recombinantes/metabolismo , Ácidos Siálicos/metabolismo , Sialiltransferasas/química , Sialiltransferasas/genética , beta-D-Galactósido alfa 2-6-SialiltransferasaRESUMEN
Platelet basic protein (PBP) was purified from the supernatant of thrombin-stimulated, washed human platelets by ion-exchange, affinity, molecular sieve, and high-performance liquid chromatography (HPLC). The NH2-terminal amino acid sequence was determined by automated Edman degradation, revealing 9 unique residues followed by 10 residues of the established low-affinity platelet factor 4/beta-thromboglobulin (LA-PF4/beta TG) sequence. Among the nine were three basic residues, accounting for the high isoelectric point of PBP. Additional evidence for precursor status includes the immunological cross-reactivity of all three species and the ability of plasmin and trypsin to produce from PBP a species resembling beta TG in charge, hydrophobicity, and size. Tryptic peptide maps of PBP and LA-PF4 obtained by reverse-phase HPLC were very similar, and from each protein, a peptide was isolated which showed the amino acid composition predicted for the COOH-terminal tryptic peptide of beta TG. Normal platelets contained predominantly LA-PF4, with PBP ranging from 10% to 30% of total beta TG antigen. This was true even when fresh platelets were lysed with trichloroacetic acid in order to provide the most complete and rapid inhibition of proteolytic activity. beta TG itself was never detected in this situation or in the release supernatant of stimulated platelets, and only rarely in unprotected lysates. In agreement with earlier results, crude preparations of PBP were mitogenic for 3T3 cells, but highly purified preparations of PBP and LA-PF4 were free of this activity.
Asunto(s)
beta-Globulinas/biosíntesis , Plaquetas/análisis , Factor Plaquetario 4/biosíntesis , Precursores de Proteínas/aislamiento & purificación , beta-Tromboglobulina/biosíntesis , Secuencia de Aminoácidos , Electroforesis en Gel de Poliacrilamida , Humanos , Sueros Inmunes , Focalización Isoeléctrica , Mitógenos , Fragmentos de Péptidos/análisis , RadioinmunoensayoRESUMEN
Infliction of non-lethal scalding was found to cause an increase in the rate of incorporation of 35S-methionine into albumin and globulin fractions of rat serum proteins, the the increase being remarkably higher for alpha- and beta-globulins than for albumin and gamma-globulins The most pronounced enhancement was associated with the 60- and 70-kd constituents of beta-globulins, the 34-, 55- and 136-kd polypeptides of alpha-2-globulins and the 50-, 60-, 125- and 145-kd polypeptides of alpha-1-globulins. The response of serum proteins to the heat shock was similar, though the changes were significantly less pronounced.
Asunto(s)
Proteínas Sanguíneas/biosíntesis , Calor , alfa-Globulinas/biosíntesis , Animales , beta-Globulinas/biosíntesis , Electroforesis , Masculino , Metionina/metabolismo , Ratas , Ratas Endogámicas , Albúmina Sérica/biosíntesis , Albúmina Sérica/metabolismo , gammaglobulinas/biosíntesisAsunto(s)
beta-Globulinas/biosíntesis , Trastornos de la Coagulación Sanguínea/complicaciones , Hipertensión/sangre , beta-Tromboglobulina/biosíntesis , Trastornos de la Coagulación Sanguínea/sangre , Femenino , Humanos , Hipertensión/complicaciones , Masculino , Agregación Plaquetaria , Preeclampsia/sangre , Embarazo , Complicaciones Cardiovasculares del Embarazo/sangreRESUMEN
Increased plasma levels of beta-thromboglobulin (beta TG) and fibrinopeptide A (FPA), markers of platelet release and thrombin generation respectively, were measured in normal women, women taking oral contraceptives, normal pregnancy and pregnant women with hypertension or pre-eclampsia. No significant increases in beta TG or FPA were found in women taking oral contraceptives. Significantly increased concentrations of beta TG, but not FPA, were found in normal pregnant women in the second and third trimester of pregnancy when compared with non-pregnant age-matched controls. In eleven women with pregnancy hypertension and thirteen women with pre-eclampsia significantly elevated levels of both beta TG and FPA were found when compared with age, parity and gestation-matched pregnant controls. Although the mean value for both beta TG and FPA in the group with pre-eclampsia was higher than the group with pregnancy hypertension, the difference was not statistically significant. These findings provide additional evidence that pre-eclampsia and pregnancy hypertension are associated with activation of the coagulation system and the platelet release reaction.
Asunto(s)
beta-Globulinas/biosíntesis , Fibrinógeno/biosíntesis , Fibrinopéptido A/biosíntesis , Hipertensión/sangre , Preeclampsia/sangre , beta-Tromboglobulina/biosíntesis , Anticonceptivos Orales , Femenino , Humanos , Embarazo , Complicaciones del Embarazo/sangre , Complicaciones Cardiovasculares del Embarazo/sangre , Primer Trimestre del Embarazo , Tercer Trimestre del EmbarazoRESUMEN
Lycurim was used in the therapy of 41 CLL patients, in 34 a positive clinical effect was found. The effect was marked in cases of CLL associated with autoimmune haemolytic anaemia. The immunodepressive property of Lycurim was confirmed by immunological investigation. It has been shown that the levels of IgG, IgA and IgM fall after Lycurim treatment of CLL patients. At the same time the T-lymphocyte count decreases and a tendency for EAC rosette-forming B-lymphocyte decrease is marked.
Asunto(s)
Eritritol/análogos & derivados , Inmunosupresores/uso terapéutico , Leucemia Linfoide/tratamiento farmacológico , Adulto , Anciano , Anemia Hemolítica Autoinmune/complicaciones , Anemia Hemolítica Autoinmune/tratamiento farmacológico , Linfocitos B , beta-Globulinas/biosíntesis , Eritritol/uso terapéutico , Femenino , Humanos , Inmunoglobulina G/biosíntesis , Leucemia Linfoide/complicaciones , Leucemia Linfoide/inmunología , Recuento de Leucocitos , Masculino , Persona de Mediana Edad , Recuento de Plaquetas , Formación de Roseta , Linfocitos T , gammaglobulinas/biosíntesisRESUMEN
When two lines of gestational human choriocarcinoma cells (GCH-1 and GCH-2) were incubated with [35S]methionine, the labeled beta 2-microglobulin was not detected on sodium dodecyl sulfate:polyacrylamide gel electrophoresis after purification of the labeled protein with affinity chromatography, using rabbit antibody against beta 2-microglobulin as the ligand. In contrast, in the case of nongestational choriocarcinoma cells originating from male stomach cells, the incorporation of [35S]methionine into beta 2-microglobulin was observed. When polyadenylate-containing messenger RNA prepared from GCH-1 cells was incubated with [35S]methionine in a rabbit reticulocyte lysate system, the labeling of beta 2-microglobulin was not shown. On the other hand, when polyadenylate-containing messenger RNA from nongestational choriocarcinoma cells was incubated in the same cell-free system, labeled beta 2-microglobulin was detected. These results indicate that beta 2-microglobulin is not synthesized in gestational human choriocarcinoma cells and at least in the case of GCH-1, beta 2-microglobulin is not synthesized owing to the lack of effective messenger RNA for beta 2-microglobulin.
Asunto(s)
beta-Globulinas/biosíntesis , Coriocarcinoma/metabolismo , ARN Mensajero/metabolismo , Microglobulina beta-2/biosíntesis , Animales , Línea Celular , Coriocarcinoma/inmunología , Electroforesis en Gel de Poliacrilamida , Femenino , Antígenos HLA , Humanos , Masculino , Melanoma , Metionina/farmacología , Peso Molecular , Embarazo , Conejos , Reticulocitos , Estómago , Microglobulina beta-2/análisisRESUMEN
Beta-thromboglobulin (beta-TG) and platelet factor four (PF4) are specific platelet proteins released when a process of platelet activation occurs. The present study was undertaken in order to measure beta-TG and PF4 both as absolute plasma value and ratio to platelet number in 69 patients with myeloproliferative disorders (MD). The aim was to establish whether the increase of the two proteins could depend on platelet number or indicated an "in vivo" platelet activation. In 74% of patients beta-TG was found elevated and PF4 was high in 68% of cases. However in 34.7% and in 31.9% of cases respectively, the elevation of the two platelet markers was correlated to platelet number and the ratio was normal. Only in about one third of cases an "in vivo" platelet activation could be admitted and this finding provides a more rational use of antiaggregating agents.
Asunto(s)
beta-Globulinas/biosíntesis , Plaquetas/fisiología , Trastornos Mieloproliferativos/sangre , beta-Tromboglobulina/biosíntesis , Adolescente , Adulto , Anciano , Calcio/análisis , Calcio/biosíntesis , Femenino , Humanos , Masculino , Persona de Mediana Edad , Recuento de Plaquetas , beta-Tromboglobulina/análisisRESUMEN
Normal human peripheral blood lymphocytes were incubated in the presence of different concentrations of interferon for various incubation periods. Subsequently, the amount of beta 2-Microglobulin and HLA-A, B and C surface antigens was estimated by means of quantitative immunofluorescence (flow cytofluorometry) and by a radioimmunoassay for beta 2-Microglobulin. It was found that the amounts of these MHC antigens increased in a dose and time-dependent way after interferon treatment. Furthermore, the influence of different temperatures on this IFN-induced increase in beta 2-Microglobulin was gradually enhanced after incubation at 37 degrees C to 39 degrees C incubation mostly suppressed the beta 2-Microglobulin increase observed at 39 degrees C. The total amount of membrane associated beta 2-Microglobulin was estimated by a radioimmunoassay. After interferon treatment a beta 2-Microglobulin increase was observed ranging from 39% to 122% in different experiments. It is shown that interferon is the substance responsible for the effects on lymphocytes reported here, because completely pure interferon-proteins had the same activity as has been shown for partially purified interferon preparations.
Asunto(s)
beta-Globulinas/biosíntesis , Antígenos de Histocompatibilidad , Interferones/farmacología , Linfocitos/efectos de los fármacos , Microglobulina beta-2/biosíntesis , Relación Dosis-Respuesta a Droga , Humanos , Cinética , Linfocitos/metabolismo , TemperaturaAsunto(s)
beta-Globulinas/biosíntesis , Lupus Eritematoso Sistémico/sangre , beta-Tromboglobulina/biosíntesis , Anticuerpos , Complejo Antígeno-Anticuerpo , Sedimentación Sanguínea , Proteínas del Sistema Complemento , Creatinina/sangre , ADN/inmunología , Reacciones Falso Positivas , Humanos , Enfermedades Renales/complicaciones , Lupus Eritematoso Sistémico/complicaciones , Nefritis/complicaciones , Recuento de Plaquetas , Sífilis/diagnósticoAsunto(s)
beta-Globulinas/biosíntesis , Neoplasias/sangre , beta-Tromboglobulina/biosíntesis , Adulto , Anciano , Ciclofosfamida/uso terapéutico , Doxorrubicina/uso terapéutico , Quimioterapia Combinada , Femenino , Fluorouracilo/uso terapéutico , Humanos , Masculino , Persona de Mediana Edad , Neoplasias/tratamiento farmacológico , Recuento de Plaquetas , Prednisona/uso terapéutico , Vincristina/uso terapéuticoRESUMEN
Serum levels of beta 2-microglobulin (beta 2-M) were found to be significantly elevated in acute viral hepatitis, chronic persistent or active hepatitis and liver cirrhosis. beta 2-M values were significantly lower in chronic persistent hepatitis than in the three other groups. Serum beta 2-M was normal in 75 asymptomatic carriers of HBsAg. Steroid therapy was followed by reduction of serum beta 2-M levels in 11 cases of chronic active hepatitis. Variations of beta 2-M were independent from that of transaminases, bilirubin and gamma-globulins.
Asunto(s)
beta-Globulinas/biosíntesis , Hepatopatías/fisiopatología , Microglobulina beta-2/biosíntesis , Enfermedad Hepática Inducida por Sustancias y Drogas/fisiopatología , Enfermedad Crónica , Hepatitis/tratamiento farmacológico , Hepatitis/fisiopatología , Hepatitis B/inmunología , Hepatitis Viral Humana/fisiopatología , Humanos , Hepatopatías/inmunología , Prednisolona/uso terapéuticoRESUMEN
Biosynthesis and regulation of expression of transplantation as detected by a monoclonal antibody to HLA-A,B,C antigens (human leucocytic antigen) and a polyclonal antiserum to beta 2-microglobulin have been investigated using radioactive amino acids and sugars to label human lymphoid cells. We found unbalanced synthesis of HLA heavy chains and beta 2-microglobulin, the latter being in excess and secreted to the extracellular medium. In DAUDI cells, which are defective in beta 2-microglobulin, no HLA-A,B,C could be detected intracellularly even in the presence of added beta 2-microglobulin. Treatment of BRI-8 cells with tunicamycin, an antibiotic which inhibits glycosylation of polypeptides, almost had no effect on the levels of beta 2-microglobulin, while it markedly decreased that of HLA heavy chains, both on the cell surface and intracellularly. Glycosylation of the HLA heavy chains appeared to be an essential requirement for the normal expression of HLA-A,B,C antigens. The translation in vitro in a messenger-dependent reticulocyte system with total polysomes obtained from BRI-8 cells showed that beta 2-microglobulin was synthesized as a precursor. This larger polypeptide was converted into mature beta 2-microglobulin when protein synthesis was performed with microsomes instead of polysomes.
Asunto(s)
beta-Globulinas/biosíntesis , Antígenos de Histocompatibilidad/biosíntesis , Microglobulina beta-2/biosíntesis , Línea Celular , Electroforesis en Gel de Poliacrilamida , Epítopos , Antígenos de Histocompatibilidad/genética , Humanos , Tejido Linfoide/metabolismo , Sustancias Macromoleculares , Biosíntesis de Proteínas , Tunicamicina/farmacologíaAsunto(s)
beta-Globulinas/biosíntesis , Replicación del ADN/efectos de los fármacos , ADN/sangre , Lectinas/farmacología , Leucocitos/metabolismo , Mercurio/farmacología , Microglobulina beta-2/biosíntesis , Células Cultivadas , Relación Dosis-Respuesta a Droga , Humanos , Cinética , Leucocitos/efectos de los fármacosRESUMEN
The S region of the murine major histocompatibility complex controls the expression of two related, serum substance-positive proteins; one (C4) has functional complement activity, whereas the other, the sex-limited protein (Slp), is hemolytically nonfunctional. The structural relationships of these molecules to each other and to their putative intracellular precursors have been examined. Radiolabeled intracellular C4 and Slp precursors were isolated from lysates of cultured peritoneal cells. The C4 and Slp precursors and their processed subunits were purified by immunoprecipitation and sodium dodecyl sulfate/polyacrylamide gel electrophoresis. Antigenically distinct precursors for C4 and Slp were demonstrated by sequential immunoprecipitation experiments in which anti-Slp-reactive molecules were precleared by exhaustive immunoprecipitation and residual C4 molecules were precipitated by antibody to serum substance. Both molecules had apparent molecular weights of 185,000. Their molecular identities as precursors of the mature C4 and Slp proteins were established in pulse-chase studies and by comparisons of their tryptic peptide profiles with those of isolated subunits from the processed proteins. When isolated alpha- or beta-subunits from C4 and Slp proteins were compared by peptide mapping, it was possible to detect multiple distinct and multiple shared peptides. This evidence indicates that the C4 and Slp proteins derive from distinct precursor polypeptides and suggests that the primary structures of the C4 and Slp alpha- and beta-subunits are different. These results support the postulate that the S region contains two discrete structural loci that specify discrete C4 and Slp proteins.