Molecular cloning and characterization of a mouse oviduct-specific glycoprotein

In the present study, we have isolated the cDNA for the mouse oviduct-specific glycoprotein (MOGP) by screening the mouse oviduct cDNA library with the bovine oviduct-specific glycoprotein (BOGP)-cDNA probe and by the 5' rapid amplification of the cDNA end (5'RACE). The total length of cDNA was determined to be 2525 base pairs (bp) by sequence analysis. The coding region contained 2163 bp translating to 721 amino acids. Based on comparisons with the N-terminal amino acid sequences of purified-BOGP and of hamster oviduct-specific glycoprotein (oviductin), it was inferred that the derived amino acid sequence contained a signal peptide region of 21 amino acids and a mature MOGP (core protein) region of 700 amino acids (76,515 daltons). It was also inferred that the mature MOGP contained three potential N-linked glycosylation sites and 24 possible O-linked glycosylation sites, and had the unique seven-residue repeat sequence (21 repeats) within the predicted sequence in the C-terminal side. The amino acid sequence of a portion of MOGP was highly homologous to that of BOGP (71% identity), baboon oviduct-specific glycoprotein (61% identity), and human oviduct-specific glycoprotein (77% identity). Significant homologies were also observed with two mammalian secretory proteins that were reported as a mammalian member of a chitinase protein family. Northern blot hybridization with a DIG-labeled probe indicated that a single message of 2.8 kb was present in total RNA prepared from oviductal tissue. In situ hybridization using MOGP-cDNA showed that a MOGP message was only detected in the oviductal epithelial cells. These results strongly suggest that a significant degree of homology exists among oviduct-specific glycoproteins of various mammalian species.