Identification, purification, and partial characterization of a novel Mr 28,000 integral membrane protein from erythrocytes and renal tubules

dc.contributor.authorSmith, Barbara L.
dc.contributor.authorDenker, Bradley M.
dc.contributor.authorAgre, Peter
dc.contributor.authorKuhajda, Francis P.
dc.description.abstractA novel Mr 28,000 integral membrane protein ("28kDa") was identified in human erythrocytes and found entirely associated with the Triton X-100 insoluble membrane skeletons. Antibodies to 28kDa reacted strongly on immunoblots with 28kDa and a diffuse region of Mr 35,000-60,000 ("HMW-28kDa"). Selective proteolytic digestions of membranes demonstrated that HMW-28kDa has an extracellular domain, and both 28kDa and HMW-28kDa have intracellular domains. 28kDa and HMW-28kDa were purified to homogeneity. Quantitative immunoblots indicate that each erythrocyte contains 120,000-160,000 copies of 28kDa. Two-dimensional iodopeptide maps of 28kDa and HMW-28kDa were nearly identical; peptide-N-glycosidase digestion of purified HMW-28kDa demonstrated that it is the N-glycosylated form of 28kDa. When concentrated, 28kDa formed a series of larger oligomers which were stable in sodium dodecyl sulfate. Of several nonerythroid tissues studied with anti-28kDa immunoblots, only kidney displayed immunoreactive 28kDa. Purified rat kidney 28kDa was nearly identical to rat erythrocyte 28kDa when compared by two-dimensional iodopeptide mapping. Immunohistochemical staining of human kidney with anti-28kDa demonstrated prominent staining over the apical brush borders of proximal convoluted tubules. A novel integral membrane protein has been purified from erythrocyte and kidney membranes. This new protein may play a role in linkage of the membrane skeleton to the lipid bilayer.en_US
dc.identifier.citationJ Biol Chem. 1988 Oct 25;263(30):15634-42.
dc.publisherAmerican Society for Biochemistry and Molecular Biologyen_US
dc.subjectMembrane Proteins/analysisen_US
dc.subjectKidney Tubules/analysisen_US
dc.titleIdentification, purification, and partial characterization of a novel Mr 28,000 integral membrane protein from erythrocytes and renal tubulesen_US
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