Sarcoplasmic reticulumThe sarcoplasmic reticulum (SR) is a membrane-bound organelle found within muscle cells that is similar to the smooth endoplasmic reticulum in other cells. The main function of the SR is to store calcium ions (Ca). Calcium ion levels are kept relatively constant, with the concentration of calcium ions within a cell being 10,000 times smaller than the concentration of calcium ions outside the cell.
Smooth muscleSmoothmuscle is one of the three major types of vertebratemuscle tissue, the others being skeletal and cardiac muscle. It can also be found in invertebrates and is controlled by the autonomic nervous system. It is non-striated, so-called because it has no sarcomeres and therefore no striations (bands or stripes). It can be divided into two subgroups, single-unit and multi-unit smooth muscle.
Second messenger systemSecond messengers are intracellular signaling molecules released by the target cell in response to exposure to extracellular signaling molecules—the first messengers. (Intercellular signals, a non-local form of cell signaling, encompassing both first messengers and second messengers, are classified as autocrine, juxtacrine, paracrine, and endocrine signaling depending on the range of the signal.)
Calcium in biologyCalcium ions (Ca) contribute to the physiology and biochemistry of organisms' cells. They play an important role in signal transduction pathways, where they act as a second messenger, in neurotransmitter release from neurons, in contraction of all muscle cell types, and in fertilization. Many enzymes require calcium ions as a cofactor, including several of the coagulation factors.
Endoplasmic reticulumThe endoplasmic reticulum (ER) is a part of a transportation system of the eukaryotic cell, and has many other important functions such as protein folding. The word endoplasmic means "within the cytoplasm", and reticulum is Latin for "little net". It is a type of organelle made up of two subunits – rough endoplasmic reticulum (RER), and smooth endoplasmic reticulum (SER).
EF handThe EF hand is a helix–loop–helix structural domain or motif 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.
KinaseIn biochemistry, a kinase (, EC2.7.-.-) is a protein enzyme that catalyzes the transfer of phosphate groups to substrates. This process is known as phosphorylation. Typically ATP is the phosphate donor. Kinases are pervasive, the human genome codes for about 500 of these enzymes. Kinases are part of the larger family of phosphotransferases.
Sequence motifNucleotide or amino-acid sequence pattern A DNA sequence motif represented as a sequence logo for the LexA-binding motif. In biology, a sequence motif is a nucleotide or amino-acid sequence pattern that is widespread and usually assumed to be related to biological function of the macromolecule. For example, an N-glycosylation site motif can be defined as Asn, followed by anything but Pro, followed by either Ser or Thr, followed by anything but Pro residue.
Signal transductionSignal transduction is the process by which a chemical or physical signal is transmitted through a cell as a series of molecular events. Proteins responsible for detecting stimuli are generally termed receptors, although in some cases the term sensor is used. The changes elicited by ligand binding (or signal sensing) in a receptor give rise to a biochemical cascade, which is a chain of biochemical events known as a signaling pathway.
PhosphorylationIn biochemistry, phosphorylation is described as the "transfer of a phosphate group" from a donor to an acceptor or the addition of a phosphate group to a molecule.
PhosphataseIn biochemistry, a phosphatase is an enzyme that uses water to cleave a phosphoric acidmonoester into a phosphate ion and an alcohol. Because a phosphatase enzyme catalyzes the hydrolysis of its substrate, it is a subcategory of hydrolases. Phosphatase enzymes are essential to many biological functions, because phosphorylation (e.g. by protein kinases) and dephosphorylation (by phosphatases) serve diverse roles in cellular regulation and signaling.
EukaryoteDomain of life whose cells have nucleiThe eukaryotes () are cellularorganisms of the domainEukaryota or Eukarya, which have a distinct cell nucleus (formed by a nuclear membrane), membrane-bound organelles and organization supported by a cytoskeleton. Extant eukaryotes are traditionally grouped into four kingdoms: animals, plants, fungi and protists.*As an Amazon Associate I earn from qualifying purchases.