The following 5-HT receptor is not a G-protein coupled receptor

Mech of action:- All 5-HT receptors (except 5-HT3) are G protein coupled receptors which function through decreasing (5-HT1) or increasing (5-HT4, 5-HT6, 5-HT7) cAMP production or by generating IP3/ DAG (5-HT2) as second messengers. The 5-HT3 is a ligand gated cation (Na+,K+) channel which on activation elicits fast depolarization. Ref:- kd tripathi; pg num:-171