Regulatory subunit of the cAMP-dependent protein kinases involved in cAMP signaling in cells. The inactive holoenzyme is composed of two regulatory chains and two catalytic chains. Activation by cAMP releases the two active catalytic monomers and the regulatory dimer. Interacts with PRKACA and PRKACB (By similarity). PRKAR1A also interacts with RFC2; the complex may be involved in cell survival. Interacts with AKAP4. Interacts with RARA; the interaction occurs in the presence of cAMP or FSH and regulates RARA transcriptional activity. Interacts with the phosphorylated form of PJA2. Interacts with CBFA2T3. Interacts with PRKX; regulates this cAMP-dependent protein kinase (By similarity). Interacts with smAKAP; this interaction may target PRKAR1A to the plasma membrane. Interacts with AICDA (By similarity). The pseudophosphorylation site binds to the substrate-binding region of the catalytic chain, resulting in the inhibition of its activity. Belongs to the cAMP-dependent kinase regulatory chain family.