The amine transmitters are not yet completely characterized functionally, but
what is known is quite different than the known actions of the amino acids.
Except for the cholinergic nicotinic receptor, whose receptor is directly a part
of its activated cation ion channel, the other amines act at receptors that are
indirectly coupled to ion channels, and influence their ion flow through
intermediate regulatory proteins, such as the "G*"  (guanine) binding proteins
that can activate or  inhibit second messenger generating enzymes, such as
adenylate cyclase.