MOLECULAR-CLONING AND FUNCTIONAL EXPRESSION OF MOUSE CONNEXIN-30, A GAP JUNCTION GENE HIGHLY EXPRESSED IN ADULT BRAIN AND SKIN

A new gap junction gene isolated from the mouse genome codes for a con nexin protein of 261 amino acids, Because of its theoretical molecular mass of 30.366 kDa, it is named connexin-30. Within the connexin gene family, this protein is most closely related to connexin-ae (77% amin o acid sequence identity). The coding region of mouse connexin-30 is u ninterrupted by introns and is detected in the mouse genome as a singl e copy gene that is assigned to mouse chromosome 14 by analysis of mou se x hamster somatic cell hybrids. Abundant amounts of connexin-30 mRN A (two transcripts of 2.0 and 2.3 kilobase pairs) were found after 4 w eeks of postnatal development in mouse brain and skin, Microinjection of connexin-30 cRNA into Xenopus oocytes induced formation of function al gap junction channels that gated somewhat asymmetrically in respons e to transjunctional voltage and at significantly lower voltage (V-o = +38 and -46 mV) than the closely homologous connexin-26 channels (V-o = 89 mV). Heterotypic pairings of connexin-30 with connexin-as and co nnexin-32 produced channels with highly asymmetric and rectifying volt age gating, respectively. This suggests that the polarity of voltage g ating and the cationic selectivity of connexin-30 are similar to those of its closest homologue, connexin-26.