Glutamate at position 227 of junctophilin-2 is involved in binding to TRPC3.
Canonical-type transient receptor potential cation channel type 3 (TRPC3) allows the entry of extracellular Ca(2+) and Na(+) into various cells. In mouse skeletal myotubes, functional interaction between TRPC3 and RyR1 (ryanodine receptor type 1/Ca(2+)-release channel on sarcoplasmic reticulum membrane) regulates the gain of excitation-contraction coupling. Junctophilin-2 (JP2) is a TRPC3-interacting protein in mouse skeletal myotubes. Based on these knowledge from bona-fide TRPC3-expressing cells, to identify critical binding region(s) of JP2 that participate in binding to TRPC3, various JP2 portions were subjected to co-immunoprecipitation assay with intact TRPC3 from rabbit skeletal muscle. A region covering 143 to 234 amino acids of JP2 (F1-2) was the most efficient portion binding to TRPC3. Through mutational studies, we found that the binding ability of JP2 to TRPC3 was mainly due to glutamate in the F1-2 region (E227). This substantial binding between JP2 and TRPC3 suggests that JP2 can be a regulatory protein of TRPC3 and/or TRPC3-mediated Ca(2+) homeostasis in skeletal muscle.
Woo
Jin Seok
JS
Department of Physiology, The Catholic University of Korea, Seoul, Korea.
Hwang
Ji-Hye
JH
Ko
Jae-Kyun
JK
Kim
Do Han
DH
Ma
Jianjie
J
Lee
Eun Hui
EH
D000818:Animals; D001665:Binding Sites; D018698:Glutamic Acid; D008565:Membrane Proteins / Q000378:metabolism*; D051379:Mice; D009124:Muscle Proteins / Q000378:metabolism*; D010446:Peptide Fragments / Q000378:metabolism; D011485:Protein Binding; D011817:Rabbits; D050052:TRPC Cation Channels / Q000378:metabolism*
D018698:Glutamic Acid; D008565:Membrane Proteins; D009124:Muscle Proteins; D010446:Peptide Fragments; D050052:TRPC Cation Channels; C104603:TRPC3 cation channel; C412507:junctophilin; C000589042:JP2 protein, mouse