Isolation and characterization of the MHC linked beta-type proteasome subunit MC13 cDNA.

We have cloned and analysed the second mouse MHC-linked proteasome subunit, designated MC13, which appears to be homologous to the human RING10 proteasome protein. The isolated cDNA has an ORF encoding a protein of 276 amino acids with a molecular weight of ca. 30 kDa. Sequence alignment reveals that the subunit MC13 and several other mammalian proteasome subunits are encoded by a second proteasome gene family. This second gene family encodes subunits of the beta-type, reveals striking sequence similarities with the beta-subunit of archaebacterial proteasomes and is related to, but distinct from, the genes encoding the so-called alpha-type subunits.