is an enzyme which converts ATP, a small molecule

其功能是转化ATP ATP是一种
that is inside all of our cells.

存在于所有细胞中的小分子物质
ATP is famous for its ability to store energy

ATP分子的有名之处在于它能够储能
but it's also a messenger molecule.

但它也是一类信使分子
When a certain enzyme is activated inside cells,

细胞内的某种酶被激活后
ATP gets converted into a molecule called cyclic AMP, and

ATP就能转化为一种叫cAMP的分子
cyclic AMP is an example of one of these molecules called second messengers.

cAMP是一种第二信使分子的范例
It gets produced in response to a signal

这类分子的产生是对信号做出的一种反应
so there's a binding of a ligand to a receptor,

当配体和受体结合时
the enzyme that does this conversion

催化这种转化过程的酶被激活
is activated and more cycle AMP is released.

更多的cAMP释放出来
As cyclic AMP levels rise inside the cell,

细胞内cAMP水平升高