Junctophilins: a novel family of junctional membrane complex proteins.
Junctional complexes between the plasma membrane (PM) and endoplasmic/sarcoplasmic reticulum (ER/ SR) are a common feature of all excitable cell types and mediate cross-talk between cell surface and intracellular ion channels. We have identified the junctophilins (JPs), a novel conserved family of proteins that are components of the junctional complexes. JPs are composed of a carboxy-terminal hydrophobic segment spanning the ER/SR membrane and a remaining cytoplasmic domain that shows specific affinity for the PM. In mouse, there are at least three JP subtypes: JP-1, -2, and -3. JP-2 is abundantly expressed in the heart, and mutant mice lacking JP-2 exhibited embryonic lethality. Cardiac myocytes from the mutant mice showed deficiency of the junctional membrane complexes and abnormal Ca2+ transients. Our results suggest that JPs are important components of junctional membrane complexes.
Takeshima
H
H
Division of Cell Biology, Institute of Life Science, Kurume University, Aikawa-machi, Fukuoka, Japan. takeshim@lsi.kurume-u.ac.jp
Komazaki
S
S
Nishi
M
M
Iino
M
M
Kangawa
K
K
D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D020013:Calcium Signaling; D002462:Cell Membrane / Q000378:metabolism; D017931:DNA Primers / Q000235:genetics; D004721:Endoplasmic Reticulum / Q000378:metabolism; D008297:Male; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000378:metabolism / Q000648:ultrastructure; D009206:Myocardium / Q000378:metabolism / Q000648:ultrastructure; D011817:Rabbits; D012519:Sarcoplasmic Reticulum / Q000378:metabolism; D017386:Sequence Homology, Amino Acid; D014018:Tissue Distribution
D017931:DNA Primers; D008565:Membrane Proteins; C412507:junctophilin