Coding Sequence of a Hyaluronan Synthase Homologue Expressed during Expansion of the Mouse Cumulus–Oocyte Complex

Maturation of mammalian cumulus cell–oocyte complex in the preovulatory follicle involves the deposition of a hyaluronan-rich extracellular matrix by the cumulus cells. In this study, we report the complete coding sequence of a novel mouse hyaluronan synthase homologue expressed in cumulus cell–oocyte complexes induced to expandin vivo.The time frame of mRNA expression of this molecule correlates well with previous biochemical and immunohistochemical findings on the initiation of hyaluronan synthesis in maturing preovulatory follicles. Evolutionary comparison of the vertebrate hyaluronan synthase homologues indicates that there are at least two genes that code for these proteins.