The gene family encoding a major glycoprotein in the murine submaxillary glands
A gene family encoding msp36, a major product of the mouse submaxillary gland, was shown by Southern analysis and genomic cloning to contain approximately ten related genes. Restriction and heteroduplex mapping, allied to hybridisation of the cDNA to cloned genomic fragments, have elucidated the overall structures of some of the msp36-related genes, and in one case have produced a precise gene arrangement. The use of specific oligonucleotide probes has further refined these structures and demonstrated the close physical linkage of six of the genes in "head-to-head", "head-to-tail" and "tail-to-tail" configurations. They have also implied the presence of an intron-less msp36-related sequence which is probably a pseudogene. Investigations at the mRNA level have led to the conclusions that the expression of the msp36 genes is tissue-specific and not androgen-regulated. There appear to be two classes of mature transcript which may originate by differential splicing or, more likely, be the products of diferent genes. The function of msp36 is not known, but from the cDNA-derived primary protein sequence it seems likely that it is a secreted glycoprotein. Several possible identities are discounted on the basis of amino-acid composition, immunoprecipitation and the tissue-specificity of the expression.