Identification of a cDNA encoding tubulointerstitial nephritis antigen.
Tubulointerstitial nephritis antigen (TIN-ag) is a 58-kDa basement membrane glycoprotein that is recognized by human autoantibodies in certain forms of tubulointerstitial nephritis. To further characterize this macromolecule and isolate cDNAs encoding TIN-ag, amino acid sequences from tryptic peptides were used to design and synthesize primers in order to amplify a probe for screening a rabbit kidney cortex cDNA library. A cDNA encoding TIN-ag was cloned and sequenced. The predicted amino acid sequence deduced from this cDNA includes the chemically determined sequences of peptides derived from TIN-ag, supporting its authenticity. The predicted amino acid sequence also shows that the carboxyl-terminal region of the molecule exhibits a 30% homology with human preprocathepsin B, a member of the cysteine proteinase family of proteins. A domain in the amino-terminal region of TIN-ag contains an epidermal growth factor-like motif that shares homology with laminin A and S chains, alpha 1 chain of type I collagen, von Willebrand's factor, and mucin, suggesting structural and perhaps functional similarities among these molecules. Immunoprecipitation of in vitro generated recombinant protein using a TIN-ag-specific monoclonal antibody (A8), confirms the identity of the isolated TIN-ag cDNA. In this report the cDNA and predicted amino acid sequences of TIN-ag are presented. Knowledge of the primary structure of TIN-ag will facilitate our understanding of the molecular structure of this novel basement membrane component and may provide clues toward understanding its functional role.
Nelson
T R
TR
Department of Laboratory Medicine and Pathology, University of Minnesota Medical School, Minneapolis 55455, USA.
Charonis
A S
AS
McIvor
R S
RS
Butkowski
R J
RJ
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D015139:Blotting, Southern; D015153:Blotting, Western; D002403:Cathepsins / Q000235:genetics; D015815:Cell Adhesion Molecules / Q000235:genetics*; D002474:Cell-Free System; D015342:DNA Probes; D018076:DNA, Complementary / Q000235:genetics; D004792:Enzyme Precursors / Q000235:genetics; D015723:Gene Library; D007672:Kidney Cortex; D008562:Membrane Glycoproteins / Q000235:genetics*; D008969:Molecular Sequence Data; D009395:Nephritis, Interstitial / Q000235:genetics*; D014176:Protein Biosynthesis; D011817:Rabbits; D017386:Sequence Homology, Amino Acid; D034501:Telomere-Binding Proteins; D014158:Transcription, Genetic
D015815:Cell Adhesion Molecules; D015342:DNA Probes; D018076:DNA, Complementary; D004792:Enzyme Precursors; D008562:Membrane Glycoproteins; D034501:Telomere-Binding Proteins; D002403:Cathepsins; C057831:preprocathepsin B