N-Terminal modifications of the 19S regulatory particle subunits of the yeast proteasome.
The yeast (Saccharomyces cerevisiae) contains three N-acetyltransferases, NatA, NatB, and NatC, each of which acetylates proteins with different N-terminal regions. The 19S regulatory particle of the yeast 26S proteasome consists of 17 subunits, 12 of which are N-terminally modified. By using nat1, nat3, and mak3 deletion mutants, we found that ... 8 subunits, Rpt4, Rpt5, Rpt6, Rpn2, Rpn3, Rpn5, Rpn6, and Rpn8, were NatA substrates, and that 2 subunits, Rpt3 and Rpn11, were NatB substrates. Mass spectrometric analysis revealed that the initiator Met of Rpt2 precursor polypeptide was processed and a part of the mature Rpt2 was N-myristoylated. The crude extracts from the normal strain and the nat1 deletion mutant were similar in chymotrypsin-like activity in the presence of ATP in vitro and in the accumulation level of the 26S proteasome. These characteristics were different from those of the 20S proteasome: the chymotrypsin-like activity and accumulation level of 20S proteasome were appreciably higher from the nat1 deletion mutant than from the normal strain.
Mesh Terms:
Acetylation, Acetyltransferases, Adenosine Triphosphate, Amino Acid Sequence, Chymotrypsin, Cysteine Endopeptidases, Gene Deletion, Mass Spectrometry, Molecular Sequence Data, Multienzyme Complexes, Proteasome Endopeptidase Complex, RNA, Ribosomal, Saccharomyces cerevisiae, Substrate Specificity
Acetylation, Acetyltransferases, Adenosine Triphosphate, Amino Acid Sequence, Chymotrypsin, Cysteine Endopeptidases, Gene Deletion, Mass Spectrometry, Molecular Sequence Data, Multienzyme Complexes, Proteasome Endopeptidase Complex, RNA, Ribosomal, Saccharomyces cerevisiae, Substrate Specificity
Arch. Biochem. Biophys.
Date: Jan. 15, 2003
PubMed ID: 12504901
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