cAMP-dependent protein kinase inhibitor beta is a member of the cAMP-dependent protein kinase inhibitor family. Studies of a similar protein in rat suggest that this protein may interact with the catalytic subunit of cAMP-dependent protein kinase and act as a competitive inhibitor. At least three alternatively spliced transcript variants encoding the same protein have been reported.

The deduced 70-amino acid protein has a calculated molecular mass of about 7.4 kD. The purified protein has an apparent molecular mass of 10.5 by SDS-PAGE.Using kinetic analysis for inhibitor activity, Van Patten et al. (1991) determined that purified PKIB is a competitive inhibitor of cAMP-dependent protein kinase.