Protein kinase description

Answer A. The description best fits the PIPj system in which protein kinase C is activated. 

Also known as microtubule associated protein kinases and early response kinases (ERKs). For more synonyms and even more complex descriptions of function, see www.brenda. uni-koeln.de/information/all enzymes.pbp4 ecno 2.7.1.37.MAPK... 

P2 and ALBP have tyrosine at position 19 (helix al). As will be described in the next section, phosphorylation by tyrosyl kinases occurs at this position. In terms of structure/function relationships, the phosphorylation of Tyr-19 is difficult to explain. If we assume a static picture for the protein as derived from the crystal structure, the tyrosine is buried and inaccessible to the protein kinase. A more detailed description of Tyr-19 will be given in Section IX,B. 

As might be noted in the preceding description, the specificity of neurotransmitter effects that are mediated by cAMP is determined at three basic levels. First of all, the nature of the neurotransmitter receptor will determine whether membrane-bound adenylate cyclase will be stimulated, inhibited, or left unaffected. Second, the nature, concentration, and intrinsic activity of the protein kinase and the phosphoprotein phosphatase will determine the pattern and degree of protein phosphorylation. Last, the identity and availability of the protein substrates will determine the ultimate biochemical consequences of cAMP elevations. 

The downstream targets of ceramide that are involved in apoptosis remain to be identified. A few potential targets have, however, been described. In A431 cells, Davis and co-workers showed that sphingomyelin induced phosphorylation of the epidermal growth factor receptor at a specific site, Thr 669 (Davis et al., 1988 Faucher et al., 1988 Countaway et al., 1989). This led to the description of a membrane-bound, Ca -independent protein kinase that is stimulated by ceramide (Mathias et al., 1991). Conversely, Hannun and co-workers have demonstrated that ceramide activates a member of the the heterotrimeric protein phosphatase 2A family in rat T9 glioma cells and have coined the term ceramide-activated protein phosphatase (CAPP) for this activity (Dobrowsky and Hannun,... 

After a brief overview of signal transduction, the text describes the structure of the seven-helix transmembrane P-adrenergic receptor and indicates how it transmits to the intracellular side of the plasma membrane a signal arising from binding the hormone epinephrine on the extracellular surface of the cell. The common features of the G proteins are presented next. The description of the information-transmission pathway from hormone stimulus to G proteins to adenylate cyclase is completed by a discussion of how cAMP activates specific protein kinases to modulate the activities of the phosphorylated target proteins. A small number of hormone molecules outside the cell results in an amplified response because each activated enzyme in the triggered cascade forms numerous products. There are many distinct seven-helix transmembrane hormone receptors. 

Adaptor Proteins. Figure 1 Adaptor protein domains. A scheme of the domain structures of some well-characterized adaptor proteins is shown. Descriptions of domain characteristics are in main text except C2, binds to phospholipids GTPase activating protein (GAP) domain, inactivates small GTPases such as Ras Hect domain, enzymatic domain of ubiquitin ligases and GUK domain, guanylate kinase domain. For clarity, not all domains contained within these proteins are shown. 

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