So in its inactive form, PKA consists of two types of subunits. So just like aspartate transcarbomolase atcase consists of catalytic and regulatory subunits, our PKA also consists of catalytic and regulatory subunits. Now, the catalytic subunit contains the active side while the regulatory subunit contains that allosteric side that binds onto the cyclic Amp. So in the absence of the allosteric effect of the cyclic adenosine monophosate molecule the coronary structure consists of two catalytic sites and these are shown in green as well as two regulatory sites. And these are shown in light brown. So this is basically one of these regulatory subunits and this is the other regulatory subunit.