In cell biology, protein kinase A (PKA) is a family of enzymes 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, including regulation of glycogen, sugar, and lipid metabolism.
The sarcoplasmic reticulum (SR) is a membrane-bound structure 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 (Ca2+). 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. 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.
The catalytic subunit α of protein kinase A is a key regulatory enzyme that in humans is encoded by the PRKACA gene. This enzyme is responsible for phosphorylating other proteins and substrates, changing their activity. Protein kinase A catalytic subunit is a member of the AGC kinase family, and contributes to the control of cellular processes that include glucose metabolism, cell division, and contextual memory. PKA Cα is part of a larger protein complex that is responsible for controlling when and where proteins are phosphorylated. Defective regulation of PKA holoenzyme activity has been linked to the progression of cardiovascular disease, certain endocrine disorders and cancers.
Serine/threonine-protein phosphatase PP1-alpha catalytic subunit is an enzyme that in humans is encoded by the PPP1CA gene.
Ryanodine receptor 2 (RYR2) is a protein found primarily in cardiac muscle. In humans, it is encoded by the RYR2 gene. In the process of cardiac calcium-induced calcium release, RYR2 is the major mediator for sarcoplasmic release of stored calcium ions.
cAMP-dependent protein kinase type I-alpha regulatory subunit is an enzyme that in humans is encoded by the PRKAR1A gene.
cAMP-dependent protein kinase type II-alpha regulatory subunit is an enzyme that in humans is encoded by the PRKAR2A gene.
A-kinase anchor protein 13 is an protein that in humans is encoded by the AKAP13 gene. This protein is also called AKAP-Lbc because it encodes the lymphocyte blast crisis (Lbc) oncogene, and ARHGEF13/RhoGEF13 because it contains a guanine nucleotide exchange factor (GEF) domain for the RhoA small GTP-binding protein.
A-kinase anchor protein 5 is a protein that in humans is encoded by the AKAP5 gene.
cAMP-dependent protein kinase catalytic subunit beta is an enzyme that in humans is encoded by the PRKACB gene.
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
A-kinase anchor protein 12, aka AKAP250, is an enzyme that in humans is encoded by the AKAP12 gene.
Peptidyl-prolyl cis-trans isomerase FKBP1B is an enzyme that in humans is encoded by the FKBP1B gene.
A kinase anchor protein 1, mitochondrial is an enzyme that in humans is encoded by the AKAP1 gene.
A-kinase anchor protein 8 is an enzyme that, in humans, is encoded by the AKAP8 gene.
cAMP-dependent protein kinase catalytic subunit gamma is an enzyme that in humans is encoded by the PRKACG gene.
A-kinase anchor protein 3 is an enzyme that in humans is encoded by the AKAP3 gene.
A-kinase anchor protein 11 is an enzyme that in humans is encoded by the AKAP11 gene.
A kinase anchor protein 10, mitochondrial is an enzyme that in humans is encoded by the AKAP10 gene.
The A-kinase anchoring proteins or A-kinase anchor proteins (AKAPs) are a group of structurally diverse proteins, which have the common function of binding to the regulatory subunit of protein kinase A (PKA) and confining the holoenzyme 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.
