| JPH4 | |||||||||||||||||||||||||
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| Identifiers | |||||||||||||||||||||||||
| Aliases | JPH4 , JP4, JPHL1, junctophilin 4 | ||||||||||||||||||||||||
| External IDs | MGI: 2443113 HomoloGene: 13034 GeneCards: JPH4 | ||||||||||||||||||||||||
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| Orthologs | |||||||||||||||||||||||||
| Species | Human | Mouse | |||||||||||||||||||||||
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| RefSeq (mRNA) | |||||||||||||||||||||||||
| RefSeq (protein) | |||||||||||||||||||||||||
| Location (UCSC) | Chr 14: 23.57 – 23.58 Mb | Chr 14: 55.11 – 55.12 Mb | |||||||||||||||||||||||
| PubMed search | [3] | [4] | |||||||||||||||||||||||
| Wikidata | |||||||||||||||||||||||||
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Junctophilin 4 is a protein in humans that is encoded by the JPH4 gene. [5]
Proteins are large biomolecules, or macromolecules, consisting of one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, responding to stimuli, providing structure to cells and organisms, and transporting molecules from one location to another. Proteins differ from one another primarily in their sequence of amino acids, which is dictated by the nucleotide sequence of their genes, and which usually results in protein folding into a specific three-dimensional structure that determines its activity.
In biology, a gene is a sequence of nucleotides in DNA or RNA that codes for a molecule that has a function. During gene expression, the DNA is first copied into RNA. The RNA can be directly functional or be the intermediate template for a protein that performs a function. The transmission of genes to an organism's offspring is the basis of the inheritance of phenotypic trait. These genes make up different DNA sequences called genotypes. Genotypes along with environmental and developmental factors determine what the phenotypes will be. Most biological traits are under the influence of polygenes as well as gene–environment interactions. Some genetic traits are instantly visible, such as eye color or number of limbs, and some are not, such as blood type, risk for specific diseases, or the thousands of basic biochemical processes that constitute life.
This gene encodes a member of the junctophilin family of transmembrane proteins that are involved in the formation of the junctional membrane complexes between the plasma membrane and the endoplasmic/sarcoplasmic reticulum in excitable cells. The encoded protein contains a conserved N-terminal repeat region called the membrane occupation and recognition nexus sequence that is found in other members of the junctophilin family. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Mar 2009].
The sarcoplasmic reticulum (SR) is a membrane-bound structure found within muscle cells that is similar to the endoplasmic reticulum in other cells. The main function of the SR is to store calcium ions (Ca2+). Calcium ion levels are kept relatively constant, with the concentration of calcium ions within a cell being 100,000 times smaller than the concentration of calcium ions outside the cell. This means that small increases in calcium ions within the cell are easily detected and can bring about important cellular changes (the calcium is said to be a second messenger; see calcium in biology for more details). Calcium is used to make calcium carbonate (found in chalk) and calcium phosphate, two compounds that the body uses to make teeth and bones. This means that too much calcium within the cells can lead to hardening (calcification) of certain intracellular structures, including the mitochondria, leading to cell death. Therefore, it is vital that calcium ion levels are controlled tightly, and can be released into the cell when necessary and then removed from the cell.
