Serine-threonine-specific receptor protein

The epinephrine receptor causes the synthesis of cyclic AMP, which is an activator of an enzyme, a protein kinase C (see Figure 12-11). Protein kinases transfer phosphate from ATP to the hydroxyl group on the side chain of a serine, threonine, or tyrosine. Protein kinase C is a serine-specific kinase. Protein kinase C is a tettamer composed of two regulatory (R) subunits and two catalytic (C) subunits. When it has cAMP bound to it, the R subunit dissociates from the C subunits. The C subunits are now catalytically active. 

Protein tyrosine phosphatases. Phosphoprotein phosphatases are integral components of the signahng systems operated by protein kinases (Sun and Tonks, 1994). Cloning data show the protein tyrosine phosphatases (PTPs) to be a family of multidomain proteins having exceptional diversity. They can be broadly divided into two groups, the transmembrane or receptor-like PTPs and the cytosolic PTPs. None of these are related to the serine-threonine specific phosphatases. This is in contrast to the protein kinases (Seer-Thr and Tyr specific), which share a common ancestry. Unlike the Ser-Thr phosphatases, in which substrate specificity is determined by associated targeting subunits, the Tyr phosphatases are all monomeric enzymes. 

A new signaling pathway of the H3 receptor involving receptor modulation of the activity of the serine/threonine-specific protein kinase Akt (protein kinase B, PKB)/GSK-3p (glycogen... 

A variety of cellular and viral proteins contain fatty acids covalently bound via ester linkages to the side chains of cysteine and sometimes to serine or threonine residues within a polypeptide chain (Figure 9.18). This type of fatty acyl chain linkage has a broader fatty acid specificity than A myristoylation. Myristate, palmitate, stearate, and oleate can all be esterified in this way, with the Cjg and Cjg chain lengths being most commonly found. Proteins anchored to membranes via fatty acyl thioesters include G-protein-coupled receptors, the surface glycoproteins of several viruses, and the transferrin receptor protein. 

Non-receptor serine/threonine kinases and dual specificity kinases cAMP-dependent protein kinase (PKA) Phosphoinositol-3-kinase (PI-3K) Cyclin-dependent kinase (CDK) Mitogen-activated protein kinase (MAPK) MAPKK (ERK)... 

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