Clustering of GABAA receptors by rapsyn/43kD protein in vitro.
Rapsyn, a 43-kDa protein on the cytoplasmic face of the postsynaptic membrane, is essential for clustering acetylcholine receptors (AChR) at the neuromuscular junction. When transfected into nonmuscle cells (QT-6), rapsyn forms discrete membrane domains and can cluster AChR into these same domains. Here we examined whether rapsyn can cluster other ion channels as well. When expressed in QT-6 cells, the GABAA receptor (human alpha 1, beta 1, and gamma 2 subunits) and the skeletal muscle sodium channel were each diffusely scattered across the cell surface. Rapsyn, when co-expressed, clustered the GABAA receptor as effectively as it clustered AChR in previous studies. Rapsyn did not cluster co-transfected sodium channel, confirming that it does not cluster ion channels indiscriminately. Rapsyn mRNA was detected at low levels in the brain by polymerase chain reaction amplification of reverse-transcribed RNA, raising the possibility of a broader role for rapsyn.
Yang
S H
SH
Department of Physiology, University of Sydney, New South Wales, Australia.
Armson
P F
PF
Cha
J
J
Phillips
W D
WD
D000818:Animals; D001921:Brain / Q000378:metabolism; D002460:Cell Line; D005347:Fibroblasts / Q000378:metabolism; D005455:Fluorescent Antibody Technique; D006801:Humans; D051379:Mice; D009124:Muscle Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D011784:Quail; D012333:RNA, Messenger / Q000378:metabolism; D011940:Receptor Aggregation; D011963:Receptors, GABA-A / Q000378:metabolism*; D011978:Receptors, Nicotinic / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014162:Transfection
D009124:Muscle Proteins; D012333:RNA, Messenger; D011963:Receptors, GABA-A; D011978:Receptors, Nicotinic; C051609:peripheral membrane protein 43K