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1.
J Biol Chem ; 271(12): 6895-902, 1996 Mar 22.
Artículo en Inglés | MEDLINE | ID: mdl-8636116

RESUMEN

Stem cell factor (SCF) is a cytokine that is active toward hematopoietic progenitor cells and other cell types, including germ cells, melanocytes, and mast cells, which express its receptor, the tyrosine kinase, Kit. SCF exists as noncovalently associated dimer at concentrations where it has been possible to study its quaternary structure; it stimulates dimerization and autophosphorylation of Kit at the cell surface. We have used recombinant versions of human SCF and human Kit extracellular domain (sKit) to study SCF-Kit interactions. By size exclusion chromatography, plus various physical chemical methods including light scattering, sedimentation equilibrium, and titration calorimetry, we demonstrate the formation of complexes containing a dimer of SCF (unglycosylated SCF1-165) plus two molecules of sKit. The concentrations of SCF and sKit in these studies were in the range of 0.35-16.2 microM. The data are analyzed and discussed in the context of several possible models for complex formation. In particular, the sedimentation data are not consistent with a model involving cooperative binding. The Kd estimate for SCF-sKit interaction, obtained by sedimentation equilibrium, is about 17 nm at 25 degrees C. With glycosylated SCF1-165, the Kd is considerably higher.


Asunto(s)
Proteínas Proto-Oncogénicas c-kit/química , Factor de Células Madre/química , Animales , Células CHO , Calorimetría , Cromatografía en Gel , Cricetinae , Escherichia coli/genética , Humanos , Luz , Proteínas Recombinantes/química , Proteínas Recombinantes/genética , Dispersión de Radiación , Factor de Células Madre/genética
2.
Blood ; 85(1): 66-73, 1995 Jan 01.
Artículo en Inglés | MEDLINE | ID: mdl-7528574

RESUMEN

c-kit encodes the transmembrane receptor tyrosine kinase (Kit) for the recently described ligand stem cell factor (SCF). We have developed an enzyme-linked immunosorbent assay for measuring soluble human Kit and we have used the assay to show high levels of soluble Kit in human serum. The distribution of soluble Kit levels was investigated among 112 normal human serum donors. The mean serum level (+/- SD) was found to be 324 +/- 105 ng/mL with the values falling between 163 ng/mL and 788 ng/mL. No correlation between soluble Kit levels and the sexes or ages of the donors was found. Partial purification using immunoaffinity chromatography allowed us to characterize the soluble Kit from pooled human serum. Antibodies generated to a 497-amino acid recombinant human soluble Kit corresponding to the N-terminal extracellular domain of the receptor recognized the serum-derived soluble Kit by immunoblotting. We found that the serum-derived soluble Kit is glycosylated, with mostly N-linked but also O-linked carbohydrate, and with terminal sialic acid residues. When compared with the recombinant human soluble Kit, the serum-derived material was similar both in size and glycosylation pattern. CNBr cleavage of the isolated serum-derived material followed by amino terminal sequencing confirmed the presence of five peptides expected for the extracellular portion of the Kit molecule. The immunoaffinity purified serum-derived soluble Kit inhibited binding of [125I]SCF to membrane-bound receptor in an in vitro assay. These results indicate that soluble Kit could modulate the activity and functions of SCF in vivo.


Asunto(s)
Proteínas Proto-Oncogénicas/metabolismo , Proteínas Tirosina Quinasas Receptoras/metabolismo , Receptores del Factor Estimulante de Colonias/metabolismo , Adulto , Secuencia de Aminoácidos , Animales , Células CHO , Cromatografía de Afinidad , Cricetinae , Ensayo de Inmunoadsorción Enzimática/estadística & datos numéricos , Escherichia coli , Femenino , Glicosilación , Humanos , Immunoblotting , Masculino , Persona de Mediana Edad , Datos de Secuencia Molecular , Proteínas Proto-Oncogénicas/química , Proteínas Proto-Oncogénicas c-kit , Proteínas Tirosina Quinasas Receptoras/química , Receptores del Factor Estimulante de Colonias/química , Proteínas Recombinantes/química , Valores de Referencia , Sensibilidad y Especificidad , Solubilidad
3.
J Hand Surg Am ; 15(1): 132-3, 1990 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-2299153

RESUMEN

An old dorsal lunate dislocation with associated multiple extensor tendon ruptures is described. Treatment consisted of proximal row carpectomy and transfer of the extensor indicis proprius to the distal stumps of the ruptured extensor tendons to the long, ring, and small fingers.


Asunto(s)
Luxaciones Articulares/cirugía , Traumatismos de los Tendones/cirugía , Transferencia Tendinosa , Traumatismos de la Muñeca/cirugía , Anciano , Humanos , Masculino , Rotura
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