Summary of the human GPCR set.

Human non-olfactory class A GPCRs were assigned to twelve sub-families according to the detailed classification reported in [6], except for the split of the MECA receptors into the AD and MEC sub-families. 7% of the human receptors could not be classified. The symbols indicate the percent of sequences with the pattern considered in human GPCRs (–, +, ++ and +++ correspond to 0%, 0 to 50%, 50 to 80% and ≥80%, respectively). Proline was searched for from position 2.58 to 2.60 in TM2 and at position 5.50 in TM5. The main proline position in TM2 is italic, normal and bold when it is observed in