Component of the 19S cap proteasome complex which acts as a regulatory subunit of the 26S proteasome, involved in the ATP-dependent degradation of ubiquitinated proteins. Component of the 19S cap proteasome complex composed of at least RPN1, RPN2, RPN3, RPN4, RPN5, RPN6, RPN7, RPN8, RPN9, RPN10, RPN11, RPN12, RPN13, RPT1, RPT2, RPT3, RPT4, RPT5, and RPT6. The 19S subcomplex associates with the 20S proteasome subcomplex to form the functional 26S proteasome. Present with 12200 molecules/cell in log phase SD medium. Belongs to the RPN13 family.