om.

CELL
MEMBRANE

 

 

HORMONE

 

 

 

aTP

CYCLIC AMP

 

 

 

 

Fig. 1: 1967 Conceptualization of an hormone-sensitive adenylyl cyclase.

The enzyme is modelled after the multisubunit enzyme aspartic transcarbamo-
ylase, in which the catalytic unit (adenylyl cyclase proper) would be under
the regulation of allosteric ligands (hormones, neurotransmitters) by inter-

acting with specific sites located on regulatory subunits (receptors). (From
Robison et al., 1967).