催化cAMP生成的腺苷酸环化酶是介导激素和神经递质对靶细胞作用的调节复合体系统的一个组成部分。这一酶系统位于细胞膜内的类脂结构之中,至少由三部分组成(图1)。位于细胞膜外表面的是能与激素和神经递质进行特异结合的受体(R);在细胞膜内表面的是催化单位(C)和核苷酸调节组分(N)。后者含有结合GTP的位点并负责介导GTP和各种激素对C活性的影响。N单位按其机能可区分为两类。一类介导激活作用(称为Ns);另一类介导GTP对腺苷酸环化酶活性的抑制作用 Adenylyl cyclase, which catalyzes the production of cAMP, is an integral part of the regulatory complex that mediates the effects of hormones and neurotransmitters on target cells. This enzyme system is located in the lipid structure of the cell membrane, at least three parts (Figure 1). Located on the outer surface of the cell membrane is a receptor (R) that specifically binds to hormones and neurotransmitters; on the inner surface of the cell membrane is the catalytic unit (C) and the nucleotide regulatory component (N). The latter contains sites that bind GTP and is responsible for mediating the effects of GTP and various hormones on C activity. N units according to their function can be divided into two categories. One type mediates activation (called Ns); the other mediates the inhibitory effect of GTP on adenylate cyclase activity