ABSTRACT
B144/LST1 is a gene encoded in the human major histocompatibility complex that produces multiple forms of alternatively spliced mRNA and encodes peptides fewer than 100 amino acids in length. B144/LST1 is strongly expressed in dendritic cells. Transfection of B144/LST1 into a variety of cells induces morphologic changes including the production of long, thin filopodia differing from those seen on transfection of a dominant active CDC42 gene. The structures are dynamically rearranging and sometimes connect one cell with another. The full effect of B144/LST1 protein on cell morphology requires the retention of at least one of the four cysteines of the peptide plus the presence of a hydrophobic segment in the protein, but requires only one of the two coding regions present in the terminal 3' exons.
Subject(s)
Blood Proteins/genetics , Major Histocompatibility Complex/genetics , Multigene Family , Pseudopodia/genetics , Tumor Necrosis Factor-alpha/genetics , Amino Acid Sequence , Animals , Blood Proteins/biosynthesis , COS Cells , Cell Differentiation , Cell Division , Conserved Sequence , Cytoplasmic Granules , Dendritic Cells/cytology , Evolution, Molecular , Humans , Immune System/cytology , Intracellular Signaling Peptides and Proteins , Membrane Proteins , Mice , Morphogenesis , Nerve Tissue Proteins/metabolism , Recombinant Proteins/biosynthesis , Wiskott-Aldrich Syndrome Protein, Neuronal , cdc42 GTP-Binding Protein/metabolismABSTRACT
The major histocompatibility complex (MHC) is located on human Chromosome 6 and includes clusters of class I, class II, and class III genes. Centromeric to the class I region is a cluster of genes designated as MHC class IV encoding genes involved in immunity and inflammation, including the 1C7 gene. The human 1C7 gene has several alternatively spliced forms and potentially codes for proteins with at least three unique carboxy termini. 1C7 mRNA in human (h1C7) is present in spleen, tonsil, B and NK cell lines, and with a different splicing pattern in liver. The 1C7 RNA and protein are present at highest levels in the germinal center of the lymphoid follicles in tonsil. The protein is expressed in NKL cells, tonsil, and unexpectedly in brain. In contrast, the mouse 1C7 gene is transcribed in liver but is predicted to be a pseudogene. However, the 1C7 homologue expressed in rat is predicted to have long stretches of amino acids essentially identical to the human protein.
Subject(s)
Killer Cells, Natural/immunology , Major Histocompatibility Complex , Receptors, Immunologic/genetics , Amino Acid Sequence , Animals , Base Sequence , Blotting, Northern/methods , COS Cells , Cell Line , DNA, Complementary , Gene Expression , Humans , In Situ Hybridization/methods , Liver/metabolism , Liver/pathology , Mice , Molecular Sequence Data , Natural Cytotoxicity Triggering Receptor 3 , Palatine Tonsil/metabolism , Palatine Tonsil/pathology , RNA, Messenger , Rats , Reverse Transcriptase Polymerase Chain Reaction/methods , Staining and Labeling/methods , TransfectionABSTRACT
Transfer RNAs of Azospirillum lipoferum were separated by two-dimensional gel electrophoresis and identified by aminoacylation. Thirty-six tRNA spots were resolved by this technique and twenty-six tRNA species have been identified. There are five tRNAs for Leu, four for Val, three for Pro, two each for Arg, Ile, Lys and Tyr, and one each for Ala, Asp, His, Phe, Ser and Thr. The tRNA (Asn) (QUU) was purified and its nucleotide sequence was determined. The A. lipoferum tRNA (Asn) (QUU) is 92% similar to B. subtilis tRNA (Asn) gene and two hypermodified nucleosides, queuosine (Q) and N-(9-beta-D Ribofuranosylpurine-6-YL)-carbamoyl)-threonine (t6A) are present in this tRNA.
Subject(s)
Azospirillum/genetics , RNA, Bacterial/chemistry , RNA, Transfer/chemistry , Base Sequence , Electrophoresis, Polyacrylamide Gel , Molecular Sequence Data , Nucleic Acid Conformation , RNA, Bacterial/genetics , RNA, Bacterial/isolation & purification , RNA, Transfer/genetics , RNA, Transfer/isolation & purification , Sequence Analysis, RNAABSTRACT
We have applied cDNA hybridization selection to nine YACs spanning 3 Mb of genomic DNA from a region centromeric to HLA-A to the histone cluster that lies telomeric to the human major histocompatibility complex (MHC). In addition to Class I genes and pseudogenes, we describe over 63 genes and 23 additional expressed sequence tags distributed throughout the region. Many of the full-length genes belong to gene families. Prominent among these are a group of genes encoding proteins showing homology to the carboxyl-terminal sequences of butyrophilin and an additional group of zinc finger genes. We also detected several previously undefined genes that are specifically expressed in cells of the immune system, indicating a more complex role of the MHC in the immune response than has been appreciated.
Subject(s)
Chromosome Mapping/methods , DNA, Complementary/genetics , Genes, MHC Class I/genetics , Transcription, Genetic , Amino Acid Sequence , Base Sequence , Chromosomes, Artificial, Yeast/genetics , Evolution, Molecular , Gene Expression , Humans , Molecular Sequence Data , Multigene Family/genetics , Pseudogenes/genetics , RNA, Messenger/genetics , Sequence Analysis, DNA , Sequence Homology, Amino Acid , Zinc FingersABSTRACT
Total tRNAs isolated from N2- and NH4(+)-grown Azospirillum lipoferum cells were compared with respect to amino acid acceptance, isoacceptor tRNA species levels and extent of nucleotide modifications. Amino-acylation of these two tRNA preparations with ten different amino acids indicated differences in the relative acceptor activities. Comparison of aminoacyl-tRNA patterns by RPC-5 column chromatography revealed no qualitative differences in the elution profiles. However, quantitative differences in the relative amounts of some isoacceptors were observed. These results indicate that alterations of relative amounts of functional tRNA species occur to match cellular requirements of the bacterial cells using N2 or NH4+ as nitrogen source. In addition, the content of modified nucleotides in total tRNAs of N2- and NH4(+)-grown cells was determined. In the NH4(+)-grown cells, content of most of the modified nucleotides decreased significantly. Based upon these results, the relationship of chargeability of tRNAs to base modifications is discussed.
Subject(s)
Amino Acids/metabolism , Azospirillum/drug effects , Nitrogen/pharmacology , Nucleotides/metabolism , Quaternary Ammonium Compounds/pharmacology , RNA Processing, Post-Transcriptional , RNA, Transfer/metabolism , Acylation , Azospirillum/metabolismABSTRACT
A genomic library was constructed from a HindIII digest of Azospirillum lipoferum chromosomal DNA in the HindIII site of pUC19. From the library, a clone, pALH64, which showed strong hybridization with 3' end labeled A. lipoferum total tRNAs and which contains a 2.9 kb insert was isolated and restriction map of the insert established. The nucleotide sequence of a 490 bp HindIII-HincII subfragment containing a cluster of genes coding for 5S rRNA, tRNA(Val)(UAC), tRNA(Thr)(UGA) and tRNA(Lys)(UUU) has been determined. The gene organization is 5S rRNA (115 bp), spacer (10 bp), tRNA(Val) (76 bp), spacer (3 bp), tRNA(Thr) (76 bp), spacer (7 bp) and tRNA(Lys) (76 bp). Hybridization experiments using A. lipoferum total tRNAs and 5S rRNA with the cloned DNA probes revealed that all three tRNA genes and the 5S rRNA gene are expressed in vivo in the bacterial cells.
