The A-kinase anchoring proteins or A-kinase anchor proteins (AKAPs) are a group of structurally diverse

proteins Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, re ...

, which have the common function of binding to the regulatory subunit of

protein kinase A In cell biology, protein kinase A (PKA) is a family of serine-threonine kinases whose activity is dependent on cellular levels of cyclic AMP (cAMP). PKA is also known as cAMP-dependent protein kinase (). PKA has several functions in the cell, in ...

(PKA) and confining the

holoenzyme An enzyme () is a protein that acts as a biological catalyst by accelerating chemical reactions. The molecules upon which enzymes may act are called substrate (chemistry), substrates, and the enzyme converts the substrates into different mol ...

to discrete locations within the cell. At least 20 AKAPs have been cloned. There are at least 50 members, often named after their molecular mass.

Function

AKAPs act as scaffold proteins wherein they bind PKA and other signaling proteins and physically tether these multi-protein complexes to specific locations, such as the nucleus, in cells. This allows specific targeting of substrates to be regulated by phosphorylation (by

PKA In chemistry, an acid dissociation constant (also known as acidity constant, or acid-ionization constant; denoted ) is a quantitative measure of the strength of an acid in solution. It is the equilibrium constant for a chemical reaction :H ...

) and dephosphorylation (by phosphatases). The dimerization and docking (D/D) domain of the regulatory subunit dimer of PKA binds with the A-kinase binding (AKB) domain (an

amphipathic In chemistry, an amphiphile (), or amphipath, is a chemical compound possessing both hydrophilic (''water-loving'', polar) and lipophilic (''fat-loving'', nonpolar) properties. Such a compound is called amphiphilic or amphipathic. Amphiphilic c ...

helix) of AKAP. The AKAPs also bind other components, including; phosphodiesterases ( PDEs) which break down cAMP, phosphatases which dephosphorylate downstream PKA targets and also other kinases ( PKC and

MAPK A mitogen-activated protein kinase (MAPK or MAP kinase) is a type of serine/threonine-specific protein kinases involved in directing cellular responses to a diverse array of stimuli, such as mitogens, osmotic stress, heat shock and proinflamm ...

). Some AKAPs are able to bind both regulatory subunits (RI & RII) of PKA and are dual-specific AKAPs (D-AKAP1 and D-AKAP2).

List of AKAPs

AKAP1 A kinase anchor protein 1, mitochondrial is an enzyme that in humans is encoded by the ''AKAP1'' gene. Function The A-kinase anchor proteins (AKAPs) are a group of structurally diverse proteins that have the common function of binding to the ...

AKAP2 A-kinase anchor protein 2 is an enzyme that in humans is encoded by the ''AKAP2'' gene. It is likely involved in establishing polarity in signaling systems or in integrating PKA-RII isoforms with downstream effectors to capture, amplify and focus ...

AKAP3 A-kinase anchor protein 3 is an enzyme that in humans is encoded by the ''AKAP3'' gene. Function The A-kinase anchor proteins (AKAPs) are a group of structurally diverse proteins, which have the common function of binding to the regulatory sub ...

* AKAP4 *

AKAP5 A-kinase anchor protein 5 is a protein that in humans is encoded by the ''AKAP5'' gene. Function The A-kinase anchor proteins (AKAPs) are a group of structurally diverse proteins, which have the common function of binding to the regulatory su ...

* AKAP6 * AKAP7 *

AKAP8 A-kinase anchor protein 8 is an enzyme that, in humans, is encoded by the ''AKAP8'' gene. Function The A-kinase anchor proteins (AKAPs) are a group of structurally diverse proteins, which have the common function of binding to the regulatory s ...

AKAP9 A-kinase anchor protein 9 is a protein that in humans is encoded by the ''AKAP9'' gene. AKAP9 is also known as Centrosome- and Golgi-localized protein kinase N-associated protein (CG-NAP) or AKAP350 or AKAP450 Function The A-kinase anchor pro ...

* AKAP10 *

AKAP11 A-kinase anchor protein 11 is an enzyme that in humans is encoded by the ''AKAP11'' gene. Function The A-kinase anchor proteins (AKAPs) are a group of structurally diverse proteins, which have the common function of binding to the regulatory s ...

* AKAP12 * AKAP13

References

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