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.
Pubmed ID: 10949023 RIS Download
Mesh terms: Amino Acid Motifs | Amino Acid Sequence | Animals | Base Sequence | Calcium Signaling | Cell Membrane | DNA Primers | Endoplasmic Reticulum | Male | Membrane Proteins | Mice | Mice, Inbred C57BL | Mice, Knockout | Molecular Sequence Data | Muscle, Skeletal | Myocardium | Rabbits | Sarcoplasmic Reticulum | Sequence Homology, Amino Acid | Tissue Distribution
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