Inositol phosphates are a group of mono- to hexa
phosphorylated inositol
Inositol, or more precisely ''myo''-inositol, is a carbocyclic sugar that is abundant in the brain and other mammalian tissues; it mediates cell signal transduction in response to a variety of hormones, neurotransmitters, and growth factors and ...
s. They play crucial roles in diverse cellular functions, such as cell growth, apoptosis, cell migration, endocytosis, and cell differentiation.
The group comprises:
*
inositol monophosphate (IP)
*
inositol bisphosphate (IP
2)
*
inositol trisphosphate (IP
3)
*
inositol pentakisphosphate
Inositol pentakisphosphate (abbreviated IP5) is a molecule derived from inositol tetrakisphosphate by adding a phosphate group with the help of Inositol-polyphosphate multikinase (IPMK). It is believed to be one of the many second messengers in ...
(IP
5)
* inositol hexaphosphate (IP
6) also known as
phytic acid
Phytic acid is a six-fold dihydrogenphosphate ester of inositol (specifically, of the ''myo'' isomer), also called inositol hexakisphosphate (IP6) or inositol polyphosphate. At physiological pH, the phosphates are partially ionized, resulting ...
, or phytate (as a salt).
Functions
Inositol triphosphate
Inositol trisphosphates act on the
inositol triphosphate receptor
Inositol trisphosphate receptor (InsP3R) is a membrane glycoprotein complex acting as a Ca2+ channel activated by inositol trisphosphate (InsP3). InsP3R is very diverse among organisms, and is necessary for the control of cellular and physiol ...
to release calcium into the cytoplasm. ''Further reading:
Function of calcium in humans''
Other
Inositol tetra-,
penta-
Numeral or number prefixes are prefixes derived from numerals or occasionally other numbers. In English and many other languages, they are used to coin numerous series of words. For example:
* unicycle, bicycle, tricycle (1-cycle, 2-cycle, 3-cy ...
, and hexa-phosphates have been implicated in
gene expression
Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product that enables it to produce end products, protein or non-coding RNA, and ultimately affect a phenotype, as the final effect. The ...
.
Inositol hexaphosphate
Inositol hexaphosphate facilitates the formation of the six-helix bundle and assembly of the immature HIV-1 Gag lattice. IP6 makes ionic contacts with two rings of lysine residues at the centre of the Gag hexamer. Proteolytic cleavage then unmasks an alternative binding site, where IP6 interaction promotes the assembly of the mature capsid lattice. These studies identify IP6 as a naturally occurring small molecule that promotes both assembly and maturation of HIV-1.
References
External links
Organophosphates
Phosphate esters
Signal transduction
Inositol
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