CDNA CLONING OF A NEW-TYPE OF SUBUNIT OF MAMMALIAN PROTEASOMES

The primary structure of a new type of subunit (RN3) of rat proteasome s (multicatalytic proteinase complexes) has been determined from the n ucleotide sequence of the cDNA. The cDNA encodes a protein of 232 amin o acids but the directly determined N-terminal amino acid sequence sug gests that the subunit is post-translationally processed to a M(r) = 2 4k form. Sequence alignments reveal a similarity of RN3 to other prote asome subunits. It can be designated a B-type proteasomal subunit but is not closely related to the beta subunit of the archaebacterial prot einase or to other members of the B group.