Cloning, characterization, and expression of the human TIN-ag-RP gene encoding a novel putative extracellular matrix protein

The human gene encoding a novel tubulointerstitial nephritis antigen (TIN-a g)-related protein (TIN-ag-RP) was isolated, and its genomic organization w as determined BLAST searches revealed the highest degree of homology to sev eral mammalian TIN-ag orthologues, and a weak homology to cathepsin B-like proteases. The 12 kb gene was mapped by fluorescence In situ hybridization to chromosome 1p34.2-3, a locus neither related to that of the human TIN-ag (6p11.2-12) nor to that of cathepsin B (8p22-23.1). The TIN-ag-RP is encod ed in ten exons with introns ranging from 83 bp to 4 kb. in addition, the g ene contained one exon in the 5'UTR, but none in the 3'UTR. Five of the 10 splice sites of the TIN-ag-RP gene were fully conserved when compared to a related gene of C. elegans, whereas only one splice site was identical to t hose found in cathepsin B genes. Furthermore, human TIN-ag-RP tagged with t he T7-epitope, was expressed in HeLa cells, and was found to be localized i n vesicular compartments as well as secreted into the medium suggesting the involvement of the endosomal trafficking pathway. Eased on the high degree of homology of the amino acid sequences and genomic organization between T IN-ag-RP and TIN-ag, we suggest that both molecules may form a distinct gro up or family of TEN-ag-like proteins. (C) 2000 Academic Press.