Characterization and distribution of albumin binding protein in
normal rat kidney.
Cessac-Guillemet, Anne Lise, Francoise Mounier, Caroline Borot,
Hilaire Bakala, Martine Perichon, Madeleine Schaeverbeke, and Jean
Schaeverbeke.
Laboratoire de Biologie Cellulaire, Universit[acute]e Paris 7, Case
7128, 2, place Jussieu, 75251 Paris CEDEX 05, France and CIME,
Universit[acute]e Paris 6, 7 quai St Bernard, 75005 Paris, France
APStracts 3:0024F, 1996.
The mechanism by which proteins that pass throught the glomerular
basal lamina are taken by proximal tubule cells is incompletely
characterized. Past work has identified the kinetics of albumin
binding to renal brush border membrane. We have now purified and
characterized albumin binding protein (ABP) and shown its
distribution in renal proximal tubular cells. ABP was purified from
rat renal proximal tubular cell brush-border membrane by affinity
chromatography with rat serum albumin-sepharose. The resulting ABP
had two apparent molecular weights (55 kDa and 31 kDa) by SDS PAGE.
Antibodies to ABP were raised in rabbits and checked by immunoassay
and immunoblotting. Light microscope immunohistochemistry showed ABP
all along the proximal tubule in the pars convoluta and in the pars
recta. Electron microscope immunohistochemistry showed labelling on
microvilli and in apical endocytic vacuoles, dense apical tubules and
lysosomes. These results indicate that ABP is involved in proximal
tubule endocytosis.
Received 19 July 1995; accepted in final form 19 January 1996.
APS Manuscript Number F240-5.
Article publication pending Am. J. Physiol. (Renal Fluid Electrolyte
Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 8 February 96