Isolation and characterization of a novel connexin gene, Cx-60, in porcine ovarian follicles.

A new member of the connexin family was isolated from the porcine ovary. The amino acid sequence deduced from the nucleotide sequence of genomic as well as complementary DNA clones predicted the reading frame encoding the 60-kDa protein product, indicating the largest molecular mass among the connexin family genes analyzed to date; we named this gene Cx-60 based on its predicted molecular mass. The features of its primary structure were compared with those of other connexin genes, and the characteristics of its expression profile were examined in mammalian ovarian follicles. Cx-60 shares significant similarities with other connexins in the transmembrane and extracellular domains, but showed a highly unique primary structure in the cytoplasmic and carboxyl-terminal domains. The Cx-60 gene was unique in that its messenger RNA was detected in both the theca interna compartment and cumulus cells in the ovary; of other tissues, Cx-60 expression was relatively evident in the colon, thymus, and spleen. Cx-60, in contrast to Cx-43, was expressed constitutively upon gonadotropin stimulation when examined in hypophysectomized rats. Taken together, these results indicate that at least the connexin genes Cx-60, Cx-43, Cx-32, Cx-30.3, and Cx-26 are expressed in porcine ovarian follicles with differing expression profiles, including cell specificity.