In the present work we examined whether the interaction between albumin molecules and thymocytes involves albumin-binding proteins (ABP). Two plasmalemma-rich fractions obtained by differential centrifugation from rat thymus lymphocytes were characterized biochemically and morphologically. These fractions were examined by ligand-blotting and ligand affinity chromatography techniques. Plasmalemma proteins separated by SDS-PAGE were electrotransferred onto nitrocellulose membranes and incubated with125I-albumin, in the presence or absence of excess native albumin. The autoradiogram revealed specific binding to two sets of polypeptides of 16–18 and 29–31 kDa, which could be blocked by native albumin. To elucidate whether albumin-binding proteins are exposed on the cell surface, intact lymphocytes were surface radioiodinated and membrane fractions prepared from them were subjected to affinity chromatography on albumin-agarose beads. The proteins thus purified had, like ABP, Mr of 16 and 31. These data indicate that ABP (i) are components of thymocyte plasma membrane, (ii) have apparent molecular mass of 16–18 and 29–31 kDa, and (iii) are exposed on the outer membrane surface.
Research Article| October 01 1996
Identification of albumin-binding proteins of thymocyte plasmalemma
1Institute of Cellular Biology and Pathology “Dr. Nicolae Simionescu”, 8, B.P. Hasdeu Street, P.O. Box: 35-14, Bucharest-79691, Romania.
2Department of Immunogenetics, Lindsley F. Kimball Research Institute, New York Blood Center, 310 E. 67th Street, New York, New York 10021.
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Ludy Dorbrila, Geo Serban, Constantina Heltianu; Identification of albumin-binding proteins of thymocyte plasmalemma. Biosci Rep 1 October 1996; 16 (5): 425–438. doi: https://doi.org/10.1007/BF01207267
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