Cell Biology Vocabulary

A class of cell-surface signal receptors for which ligands (cytokines) activate cytosolic JAK kinases associated with the receptor, which initiate intercellular signaling.

Small signaling proteins that play roles in growth and differentiation of cells, particularly in the blood and immune system. Includes interleukins, interferons, and erythropoietins (Epo).

A homologous region on many signal-transduction proteins (incl. STAT transcription factors) which bind to phosphotyrosine residues (i.e. on JAK), allowing proteins containing SH2 domains to localize on a signal protein after the tyrosine has been phosphorylated (by tyrosine kinases).

A mutant form of a protein that inhibits the function of the wild type by interfering with its activity, such as by binding to its signaling molecules.

When signaling molecules are involved in multiple pathways, and response to a signal-induced condition can cause multiple simultaneous outcomes within a cell.

A large protein complex within cells where ubiquitinated proteins are 'sent' for degradation by proteases.

A large class of cell-surface receptors which have an intrinsic kinase in their cytosolic domain, and signal through tyrosine kinase activity which triggers intercellular signal transduction. RTKs are involved in cell proliferation, differentiation, survival, and metabolism.

A monomeric (small) G protein that promotes the formation of signal-transduction complexes at the membrane containing three sequentially acting protein kinases (kinase cascade). Ras is part of the GTPase superfamily.

An enzyme that catalyzes the transfer of a phosphate group from ATP to a specified molecule.

A family of proteins activated by the kinase cascade (MAPK cascade). MAP kinases can translocate into the nucleus and phosphorylate many different proteins.

An activator molecule for small G proteins (ex: catalyzes the formation of the active Ras-GTP complex).

A family of regulatory proteins that bind to G proteins and stimulate termination of the signaling event (ex: GAP binds to Ras-GTP complex and accelerates intrinsic GTP hydrolysis, deactivating the complex).

An isoform of phospholipase C, enzymes that cleave phospholipids just before the phosphate group. The gamma form contains SH2 domains that bind to specific phosphotyrosines and is activated by some RTKs and cytokine receptors. This helps localize the PLC to membranes so it can perform its roles in signal transduction.

The ability of cells to generate functionally destinct regions,
such as during migration.

An actin structure that forms at the late stages of cell division, after the organelles have been fully duplicated and segregated. The contractile ring constricts to separate the two daughter cells during cytokinesis.