BIO315H5 Lecture Notes - Lecture 2: Structural Motif, Guanine Nucleotide Exchange Factor, Hydrolysis
Document Summary
Lecture 2: mechanisms of cell communication (chapter 15, pp. Gtp/gdp binding: these proteins switch between an on (actively signaling) state when. Gap: gtpase-activating proteins; drive the proteins into an off state by increasing the rate of hydrolysis of bound gtp. Gef: guanine nucleotide exchange factor; activate gtp-binding proteins by promoting the release of bound gdp, which allows a new gtp to bind. How to ensure signal and response specificity: high-affinity, specific interactions with appropriate signaling partners. Protein kinases have active sites that recognize specific amino acid residues around the phosphorylation site s: signal threshold required for response, they only respond when upstream signal reaches a high concentration or activity level. Constitutive phosphatases reduce background or noise : localization of specific signaling proteins to the same region of the cell. Localizing the site where intracellular signalling proteins act is importanr to ensure that a specific (and appropriate) response is mounted while minimizing unwanted cross-talk with other signalling pathways.
