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Primary structures of two homologous subunits of PA28, a γ‐interferon‐inducible protein activator of the 20S proteasome
Author(s) -
Willy Patricia J.,
Mott Joni D.,
Slaughter Clive A.,
DeMartino George N.
Publication year - 1995
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(95)00492-r
Subject(s) - proteasome , homologous chromosome , activator (genetics) , chemistry , microbiology and biotechnology , protein subunit , interferon , biology , biochemistry , virology , gene
The primary structures of two proteins that comprise PA28, an activator of the 20S proteasome, have been determined by cDNA cloning and sequencing. These protein subunits, termed PA28α and PA28β, are about 50% identical to one another and are highly conserved between rat and human. PA28α and PA28β are homologous to a previously described protein, Ki antigen, whose function is unknown. PA28α, but neither PA28β nor Ki antigen, contains a ‘KEKE motif’, which has been postulated to promote the binding of proteins having this structural feature. PA28α and PA28β were coordinately regulated by γ‐interferon, which greatly induced mRNA levels of both proteins in cultured cells. The mRNA level of the Ki antigen also increased in response to γ‐interferon treatment, but the magnitude of the increase was less than that for the PA28s, and the effect was transient. These results demonstrate the existence of a new protein family, at least two of whose members are involved in proteasome activation. They also provide the basis for future structure/function studies of PA28 subunits and the determination of their relative physiological roles in the regulation of proteasome activity.