Kinase Group TK

This group phosphorylates almost exclusively on tyrosine residues, as opposed to most other kinases that are selective for serine or threonine. The group appears to be the youngest of kinase groups, as it is absent from plants and unicellular organisms like Dictyostelium and yeast. It functions particularly in the relay of extracellular signals into the cell: over half of TKs are cell surface receptors (RTKs) and many of the others function close to the surface of the cell.

Families

This group is very well studied, and quite diverse, and so has the largest number of distinct families of any group.

Receptor Tyrosine Kinases (RTKs)

FGFR

Fibroblast Growth Factor Receptors.

VEGFR

Vascular Endothelial Growth Factor Receptors. Three of these, in vertebrates, control the develoment of the vascular system (blood) and lympatic system, and are important targets for anti-angiogenesis drugs for cancer. No clear VEGFR exists outside of vertebrates, but Drosophila has a pair of genes that appear to be intermediate between VEGFR and PDGFR families

PDGFR

Platelet-derived growth factor receptors. In vertebrates, these include a pair of PDGFRs, as well as the realted receptors fms (CSF1R), kit and flt3, growth factor receptors involved in blood cell development, testictular development and some other processes. As above, insects have receptors that are intermediate between PDGFR and VEGFR families.

EGFR

Epidermal Growth Facor Receptors. (also in invertebrates...)

Tie

This pair of vertebrate-only receptors is involved in angiogenesis.

Trk

Neurotrophin receptors; important growth factor receptors that act on neuronal cells.

Eph

Ephrin receptors guide maping of optical neurons to the brain, among other functions. Invertebrates have just a single member of the family, which explodes into 14 members in vertebrates.

DDR

Discoidin Domain Receptors

CCK4

A famiyl with a single member that is found from human all the way down to hydras. Curiously, the kinase domain is predicted to be catalytically inactive in all species, and little is known about the CCK4 function.

InsR

Receptors for insulin and insulin-like growth factor (IGF), these are important in energy homeostasis and cell growth and aging.

Lmr

A vertebrate-only family of three, with virtually no extracellular region, and a long, divergent sequence beyond the cytoplasmic kinase domain (hence Lemur, after the long tail). Little is known about this family.

Kin-16 and Kin-9

These two families exist only in nematodes, where they are recently expanded. They are weakly similar to FGF receptors, and a pair of them have been weakly implicated in aging.

Non-receptor tyrosine kinase families

Also known as Cytoplasmic Tyrosine Kinases (CTKs) though many function in complexes tethered to the plasma membrane. Many contain SH2 and/or SH3 domains which cause them to be activated by phospo-tyrosine, often by activated receptor tyrosine kinases. SH2-containing families include all but Ack, Jak, and Fak

Jak

Janus Kinases. These are activated by receptor tyrosine kinases and in turn activate the STAT transcription factors which then translocate and activate gene expression in the nucleus.

Fak

Focal Adhesion Kinase, and its close relative Pyk2.