title: Isolation and characterization of a cDNA for osteopontin-k: a kidney cell adhesion molecule with high homology to osteopontins.
abstract: Screening of a bovine renal cDNA library with MAbs resulted in the isolation of a 1447 bp cDNA. This cDNA (pBk2.1) was sequenced and shown to contain an open reading frame with a putative protein of 261 amino acids, with a molecular weight of 29,573 (minute leader sequence) and a hydrophobic leader sequence of 16 amino acids. pBk2.1 was shown to share a high level of nucleic acid sequence homology over portions of its sequence to human, porcine, mouse, and rat osteopontins (40-60%). The peptide (osteopontin-k) had a potential glycosylation site (Asn-X-Ser/Thr), a GRGDS receptor binding region, a high level of asparagine residues, and a high abundance of acid amino acids characteristic of osteopontin-like cell adhesion molecules. The N-terminal amino acid region of pBk2.1 (the first 82 amino acids) and 42 amino acids at the C terminus had the highest level of homology with the osteopontins at 86%. The middle portion of the peptide had greatly reduced homology, ranging from 50% (amino acids 83-174) to 12% (amino acids 175-219). There were also deletions and additions of sequence in osteopontin-k that were not found in the other osteopontins. The homologies suggest that these proteins are highly related and may be derived from a common gene by alternative splicing. A 678 bp cRNA probe constructed from pBk2.1, containing a region with low homology to the osteopontins (amino acids 183-219 with less than 20% homology, plus amino acids 220-261 and untranslated sequence), was used in northern blots and RNAse protection assays.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Physiology and Neurobiology, University of Connecticut, Storrs.
authors.forename: J F
authors.initials: JF
authors.lastname: Crivello
authors.forename: E
authors.initials: E
authors.lastname: Delvin
mesh_terms: D000818:Animals; D001483:Base Sequence; D002417:Cattle; D004247:DNA / Q000737:chemistry*; D007672:Kidney Cortex / Q000737:chemistry*; D008969:Molecular Sequence Data; D053495:Osteopontin; D015347:RNA Probes; D012333:RNA, Messenger / Q000737:chemistry*; D012795:Sialoglycoproteins / Q000737:chemistry*
chemical_list: D015347:RNA Probes; D012333:RNA, Messenger; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; C506896:Spp1 protein, mouse; C506897:Spp1 protein, rat; D053495:Osteopontin; D004247:DNA