Antibodies to SPARC inhibit albumin binding to SPARC, gp60, and microvascular endothelium

摘要: Albumin, through its binding to the endothelial glycocalyx, functions as a major determinant of capillary permeability and carrier for various small molecules in transcytosis across continuous endothelium via plasma-lemmal vesicles. Several albumin-binding proteins (ABP) have been identified: three membrane-associated ABP, which we call gp60, gp30, gp18, one secreted protein, acidic rich cysteine (SPARC). In this study, used antiserum raised against bovine SPARC (BON) investigate possible interrelationships among ABP better understand their role transcytosis. BON not only interacted with by cultured but also recognized gp60 lysates rat, human, cells. Purified inhibited interaction gp60. immunoglobulin (Ig)G specifically albumin both extracts. This effect was eliminated preabsorption immobilized SPARC. significantly microvascular cells Anti-SPARC peptide sera were tested, serum encompassing an NH2-terminal region did inhibit binding; gp30 gp18 any these anti-SPARC antibodies. These results suggest that are functionally immunologically related may share common domain. appears be mediator endothelium.