Possible Interaction: Alanine and Serotonin

“Mutation of either serine-154 or threonine-158 to alanine significantly reduced response of 5-HT1BR to 5-HT.”

“In contrast, substitution of phenylalanine 331 in transmembrane region VI by alanine increased the affinity of 5-HT for the uncoupled conformation 11-fold thus reducing the agonist low-affinity to agonist high-affinity (K(il)/K(ih)) ratio 5-fold.”

“Replacement of the aspartic acid 352 by alanine reduced high-affinity binding of 5-HT.”

“The alanine substitution led to an 18-fold reduction in 5-HT affinity and the cysteine substitution to an intermediate 5-fold decrease.”

“Propranolol isomers failed, but the dl- and l-isomer antagonized the inhibitory responses to NA and 5-HT respectively.”

“Increasing concentrations of serotonin (1 nM-0.1 mM) produced a concentration-dependent decrease in the rate of alanine and glutamine release from muscle; intracellular levels of these amino acids were also decreased slightly by serotonin.”

“These data indicate that serotonin inhibits alanine and glutamine synthesis and release from intact skeletal muscle.”

“Thus D-PCPA, like its L-isomer , inhibits 5-HT synthesis.”

“Interestingly, replacement of Tyr-434 with alanine increases the affinity of VMAT2 for both serotonin and dopamine and reduces the rate of dopamine transport.”