PHC230H1 Study Guide - Schizophrenia, Cholera Toxin, Haloperidol
Document Summary
Alanine scanning mutagenesis: substitutes each amino acid with alanine one at a time. Alanine substitution of several a. a. residues on the m-achr reduced its affinity for nms and ach. The w. t. a 1b-receptor has alanine at residue 293, and alanine is the only a. a. which results in a constitutive activity of zero. Substitution with lysine and glutamic acid resulted in very high levels of constitutive activity (bad). Alanine scanning mutagenesis: can be used to infer the mechanism of action of catecholinergic drugs on b -receptors. By knocking out ser-207, a drug with a para- hydroxy stimulated activity, while a drug with a meta-hydroxy did not. In contrast, the opposite occurred when ser-204 was knocked out. 207 interacts with a para-hydroxyl, and ser-204 interacts with the meta-hydroxyl. Normally, the anterior pituitary secretes tsh hormone, which stimulates ac activity in thyrocytes to raise camp levels. This then produces thyroxine and triiodothyronine, which negatively feeds back to stop tsh secretion.
