Characterization of Human Junctophilin Subtype Genes

• Published in: Biochemical and biophysical research communications Vol. 273; no. 3; pp. 920 - 927
• Main Authors: Nishi, Miyuki, Mizushima, Akiko, Nakagawara, Kan-ichi, Takeshima, Hiroshi
• Format: Journal Article
• Language: English
• Published: United States Elsevier Inc 14.07.2000
• Subjects: Amino Acid Sequence; Animals; Base Sequence; Ca2+ release channel; Chromosome Mapping; Chromosomes, Human, Pair 20; Chromosomes, Human, Pair 8; Cloning, Molecular; DNA; endoplasmic reticulum; Exons; genomic organization; Humans; intracellular Ca2+ store; Introns; Junctophilin; Membrane Proteins - chemistry; Membrane Proteins - genetics; Mice; Molecular Sequence Data; peripheral coupling; Protein Isoforms - chemistry; Protein Isoforms - genetics; Rabbits; RNA, Messenger - genetics; ryanodine receptor; sarcoplasmic reticulum; subsurface cisternae; triad junction; Ca2+ release channel; intracellular Ca2+ store; junctophilin; peripheral coupling; subsurface cisternae; triad junction; genomic organization; ryanodine receptor; endoplasmic reticulum; sarcoplasmic reticulum
• ISSN: 0006-291X; 1090-2104
• DOI: 10.1006/bbrc.2000.3011

Junctophilin (JP) subtypes, namely JP-1, 2, and 3, have been currently identified in excitable cells and constitute a novel family of junctional membrane complex proteins. Our studies have suggested that JPs take part in the formation of junctional membrane complexes by spanning the membrane of the intracellular Ca2+ store and interacting with the cell-surface membrane. In this report we describe the primary structures, genomic organization, and tissue distribution of human JP subtypes. By cloning and analyzing human genomic DNA segments, the protein-coding sequence interrupted with four introns was defined in each JP gene. The deduced human JP subtypes shared characteristic structural features with their rabbit and mouse counterparts. Genomic mapping demonstrated that JP genes do not cluster on the human genome. RNA blot hybridization indicated that tissue-specific expression patterns of JP genes in human are essentially the same as those in mouse; skeletal muscle contained both JP-1 and JP-2 mRNAs, the heart predominantly expressed JP-2 mRNA, and the brain specifically contained JP-3 mRNA. In the light of this, we propose intramolecular domains of JP subtypes based on the structural and functional characteristics.