Activator complexes containing the proteasomal regulatory ATPases S10b (SUG2) and S6 (TBP1) in different tissues and organisms.
Each 19S regulator of the 26S proteasome contains six ATPase subunits as well as many (>14) non-ATPase protein subunits. The ATPase subunits have been detected in other complexes which may regulate transcription and possibly other cellular processes. The S10b (yeast SUG2 or human p42) and the S6' (TBP1) ATPases have been found in an activator complex (modulator) prepared from bovine red cells. We have identified and partially characterised a similar activator from different human tissues (from soluble extracts of human brain, placenta and human embryonic kidney cells) and an insect: an activator is present in soluble extracts of abdominal intersegmental muscle from Manduca sexta. Activation is ATP and concentration dependent. There is no stimulation of human red cell-derived 20S proteasome by the Manduca activator ruling out 11S regulator in the preparations. Additionally, cross-species activation occurs: the Manduca activator increases the activity of rat skeletal muscle 26S proteasomes and the human placental activator similarly increases the activity of 26S proteasomes prepared from muscles from Manduca sexta. Finally, there is no evidence for other ATPases in the activator complex.
Hastings
R
R
Laboratory for Intracellular Proteolysis, School of Biomedical Sciences, University of Nottingham Medical School, Queen's Medical Centre, UK.
Walker
G
G
Eyheralde
I
I
Dawson
S
S
Billett
M
M
Mayer
R J
RJ
D000251:Adenosine Triphosphatases / Q000378:metabolism*; D000818:Animals; D002352:Carrier Proteins / Q000378:metabolism*; D002417:Cattle; D003546:Cysteine Endopeptidases / Q000378:metabolism*; D006801:Humans; D033862:Iron-Binding Proteins; D009097:Multienzyme Complexes / Q000378:metabolism*; D010447:Peptide Hydrolases / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex; D051381:Rats; D029701:Saccharomyces cerevisiae Proteins; D013045:Species Specificity; D033863:Transferrin-Binding Proteins
D002352:Carrier Proteins; D033862:Iron-Binding Proteins; D009097:Multienzyme Complexes; D029701:Saccharomyces cerevisiae Proteins; D033863:Transferrin-Binding Proteins; D010447:Peptide Hydrolases; D003546:Cysteine Endopeptidases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D000251:Adenosine Triphosphatases; C103015:RPT4 protein, S cerevisiae