MYO1A
Encyclopedia
Myosin-Ia is a protein
that in humans is encoded by the MYO1A gene
.
The protein
encoded by this gene belongs to the myosin
superfamily. Myosins are molecular motors that, upon interaction with actin
filaments, utilize energy from ATP hydrolysis
to generate mechanical force. Each myosin has a conserved N-terminal motor domain that contains both ATP-binding and actin-binding sequences. Following the motor domain is a light-chain-binding 'neck' region containing 1-6 copies of a repeat element, the IQ motif, that serves as a binding site for calmodulin
or other members of the EF-hand
superfamily of calcium-binding proteins. At the C-terminus, each myosin class has a distinct tail domain that serves in dimerization, membrane binding, protein binding, and/or enzymatic activities and targets each myosin to its particular subcellular location. The myosin-1a protein is expressed by enterocytes, the epithelial cells that line the luminal surface of the small intestine. In these cells the myosin-1a protein localizes specifically to the brush border
. Experiments indicate that the brush border population of the encoded protein turns over rapidly, while its head and tail domains interact transiently with the core actin and plasma membrane, respectively. A rapidly exchanging pool of the myosin-1a protein binds to the actin core bundle, which turns over on a much slower timescale.
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
that in humans is encoded by the MYO1A gene
Gene
A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...
.
The protein
Protein
Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...
encoded by this gene belongs to the myosin
Myosin
Myosins comprise a family of ATP-dependent motor proteins and are best known for their role in muscle contraction and their involvement in a wide range of other eukaryotic motility processes. They are responsible for actin-based motility. The term was originally used to describe a group of similar...
superfamily. Myosins are molecular motors that, upon interaction with actin
Actin
Actin is a globular, roughly 42-kDa moonlighting protein found in all eukaryotic cells where it may be present at concentrations of over 100 μM. It is also one of the most highly-conserved proteins, differing by no more than 20% in species as diverse as algae and humans...
filaments, utilize energy from ATP hydrolysis
ATP hydrolysis
ATP hydrolysis is the reaction by which chemical energy that has been stored and transported in the high-energy phosphoanhydridic bonds in ATP is released, for example in the muscles, to produce work. The product is ADP and an inorganic phosphate, orthophosphate...
to generate mechanical force. Each myosin has a conserved N-terminal motor domain that contains both ATP-binding and actin-binding sequences. Following the motor domain is a light-chain-binding 'neck' region containing 1-6 copies of a repeat element, the IQ motif, that serves as a binding site for calmodulin
Calmodulin
Calmodulin is a calcium-binding protein expressed in all eukaryotic cells...
or other members of the EF-hand
EF hand
The EF hand is a helix-loop-helix structural domain found in a large family of calcium-binding proteins. The EF-hand motif contains a helix-loop-helix topology, much like the spread thumb and forefinger of the human hand, in which the Ca2+ ions are coordinated by ligands within the loop...
superfamily of calcium-binding proteins. At the C-terminus, each myosin class has a distinct tail domain that serves in dimerization, membrane binding, protein binding, and/or enzymatic activities and targets each myosin to its particular subcellular location. The myosin-1a protein is expressed by enterocytes, the epithelial cells that line the luminal surface of the small intestine. In these cells the myosin-1a protein localizes specifically to the brush border
Brush border
A brush border is the name for the microvilli-covered surface of simple cuboidal epithelium and simple columnar epithelium cells found in certain locations of the body. Microvilli are approximately 100 nanometers in diameter and their length varies from approximately 100 to 2,000 nanometers in...
. Experiments indicate that the brush border population of the encoded protein turns over rapidly, while its head and tail domains interact transiently with the core actin and plasma membrane, respectively. A rapidly exchanging pool of the myosin-1a protein binds to the actin core bundle, which turns over on a much slower timescale.