cDNA cloning and chromosomal mapping of a mouse gene with homology to NTPases

• Published in: Mammalian genome Vol. 9; no. 2; pp. 162 - 164
• Main Authors: Chadwick, B P, Williamson, J, Sheer, D, Frischauf, A M
• Format: Journal Article
• Language: English
• Published: United States Springer Nature B.V 01.02.1998
• Subjects: Acid Anhydride Hydrolases - chemistry; Acid Anhydride Hydrolases - genetics; Amino Acid Sequence; Animals; Chromosome Mapping; Cloning; Cloning, Molecular; DNA, Complementary; Gene mapping; Homology; In Situ Hybridization, Fluorescence; Mice; Molecular Sequence Data; Nucleoside-Triphosphatase; Sequence Alignment; Sequence Homology, Amino Acid
• ISSN: 0938-8990; 1432-1777
• DOI: 10.1007/s003359900710

Nucleoside-triphosphatases (NTPases) are divalent cation-dependent transmembrane glycoproteins that hydrolyze extracellular nucleoside tri-and/or diphosphates. Several functional roles of NTPases have been proposed, including the termination of purinergic signaling, cellular adhesion, vesicular transport, purine recycling, and regulation of ectokinases by control of substrate concentration. NTPases have been identified in a broad spectrum of organisms including human, mouse, chicken, garden pea, potato, Saccharomyces cerevisiae, C. elegans, and T. gondii. We have cloned a novel mouse family member by low-stringency screening of mouse cDNA libraries with a human CD93L1 cDNA clone. A 1738-bp cDNA clone was isolated from an adult mouse testis cDNA library and sequenced. DNA sequence comparisons with the human CD39L1 cDNA sequence showed moderate DNA homology (39% identity). An open reading frame (ORF) could be detected for the cDNA sequence, but indicated that the cDNA clone did not contain the initiation methionine codon and therefore did not extend to the 5' end. Database searches with the mouse cDNA sequence identified two mouse EST clones that extended the cDNA sequence at the 5' end (Accession numbers AA116990 and AA120757). The EST clones were resequenced, and the combined DNA sequence (Acc. No. AF006482) showed an ORF from nucleotides 205 to 1599, with the ATG at nucleotide 205 having a moderate match to the initiation start site for vertebrates (AAGAAUAUGG for mNTPase versus GCCGCCAUGG). No apparent polyadenylation signal exists, although the cDNA clone contains a poly-A tail. Hydrophobicity plots with Topred-II 1.1 predict a single potential transmembrane segment close to the amino terminus of the protein, suggesting a single-pass transmembrane protein with a large extracellular domain. Two potential N-glycosylation sites can be found at amino acid positions 41 (NVSA) and at 231 (NSTF), suggesting that mNTPase is glycosylated. Database searches with the predicted protein sequence identified considerable homology to other members of the NTPase family. Figure 1 shows an alignment of the full protein sequence of mNTPase against three of the most homologous known NTPases from garden pea (Acc. No. S48859), potato (Acc. No. U58597), and Saccharomyces cerevisiae (Acc. No. L19560). The mNTPase protein shares more than 30% amino acid identity with the three other NTPases.