City College of CUNY
Department of Chemistry
Biochemistry Seminar
Wednesday, May 17, 2000
Room J1027
11:15 AM
Michael V. L. Bennett
Professor and Chair of Neuroscience
Albert Einstein School of Medicine Connexins: the family of vertebrate
Gap-junction-forming proteins
Abstract
Gap junction proteins in vertebrates (and probably also in ascidians,
echinoderms and other deuterostomes) comprise a family with some 16
members in rodents and presumably humans. Gap junctions provide small
diameter aqueous channels connecting the cytoplasm of adjacent cells, and
allow intercellular passage of ions and molecules up to a molecular
weight of about 1 kDa. They mediate both electrical and chemical
coupling. They are gated by a number of stimuli, including
transjunctional voltage, low pH and various chemicals such as higher
alcohols. Some connexins form "hemichannels" that function
without being connected to another hemichannel in an apposed cell.
Hemichannels are readily studied in excised patches, which permits high
electrical resolution and rapid solution changes. Insights
from these studies can be generalized to intercellular
channels. Genetic diseases associated with connexin mutations
include a peripheral demyelinating neuropathy (CMTX), nonsyndromic
deafness, erythrodermia variabilis and cataract.