Virtual cloning, functional expression, and gating analysis of human connexin31.9.
We have identified a novel gap junction gene by searching the human genome sequence database that encodes a protein designated as connexin31.9 (Cx31.9). Cx31.9 was most homologous to human Cx32.4 and did not cluster with either the purported alpha- or beta-connexin subfamilies. Expression of Cx31.9 was detected by RT-PCR in human mRNA from several tissues including cerebral cortex, heart, liver, lung, kidney, spleen, and testis. A partial Cx31.9 sequence was also represented in the human Expressed Sequence Tag database. Cx31.9 formed intercellular channels in both paired Xenopus oocytes and transfected neuroblastoma N2A cells that were distinguished by an apparent low unitary conductance (12-15 pS) and a remarkable insensitivity to transjunctional voltage. In contrast, Cx31.9 channels were gated by cytoplasmic acidification or exposure to halothane like other connexins. Cx31.9 was able to form heterotypic channels with the highly voltage-sensitive Xenopus Cx38 (XenCx38), which provides an opportunity to study gating in heterotypic channels formed by hemichannels (connexons) composed of connexins with widely divergent properties. Thus Cx31.9 is a novel human connexin that forms channels with unique functional properties.
White
Thomas W
TW
Department of Physiology and Biophysics, State University of New York, Stony Brook 11794-8661, USA. thomas.white@sunysb.edu
Srinivas
Miduturu
M
Ripps
Harris
H
Trovato-Salinaro
Angela
A
Condorelli
Daniele F
DF
Bruzzone
Roberto
R
D000328:Adult; D000818:Animals; D002460:Cell Line; D003001:Cloning, Molecular / Q000379:methods; D019295:Computational Biology; D017630:Connexins / Q000096:biosynthesis / Q000235:genetics* / Q000378:metabolism; D030541:Databases, Genetic; D020224:Expressed Sequence Tags; D015870:Gene Expression / Q000502:physiology*; D006221:Halothane / Q000494:pharmacology; D006801:Humans; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D008297:Male; D008969:Molecular Sequence Data; D009865:Oocytes / Q000378:metabolism; D009928:Organ Specificity; D018408:Patch-Clamp Techniques; D010802:Phylogeny; D012333:RNA, Messenger / Q000096:biosynthesis; D016415:Sequence Alignment; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D014162:Transfection; D014982:Xenopus laevis
D017630:Connexins; C468137:GJD3 protein, human; D012333:RNA, Messenger; C102630:connexin 38; D006221:Halothane