Phosphorylation and ubiquitination of the 26S proteasome complex.
This article reviews recent studies from our laboratory on protein regulators of the proteasome (multicatalytic proteasome complex) in red blood cells. A 240-kD inhibitory component (CF-2) exists in 26S proteasome complexes in a form which is conjugated to ubiquitin. Interestingly, this factor was shown to be identical to delta-aminolevulinic acid dehydratase (ALAD), involved in heme synthesis. A distinct 200-kD inhibitor of the proteasome is not present in the 26S complex. A 32-kD subunit of the 20S proteasome appears to be important for the latency of this core protease. Multiple isoelectric variants of the 32-kD subunit are consistent with phosphorylation. Another 20S proteasome subunit of 30 kD molecular weight is phosphorylated at specific serine residues by copurifying casein kinase II. It is suggested that ubiquitination and phosphorylation may account for at least part of the ATP dependency associated with the 26S proteasome complex. These modifications may play a role in the activity, assembly, translocation and/or turnover of this particle.
Etlinger
J D
JD
Department of Cell Biology and Anatomy, New York Medical College, Valhalla 10595.
Li
S X
SX
Guo
G G
GG
Li
N
N
D000255:Adenosine Triphosphate / Q000378:metabolism; D047390:Casein Kinase II; D004912:Erythrocytes / Q000378:metabolism; D006801:Humans; D008970:Molecular Weight; D010447:Peptide Hydrolases / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D000623:Porphobilinogen Synthase / Q000378:metabolism; D011480:Protease Inhibitors / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D014452:Ubiquitins / Q000378:metabolism*
D011480:Protease Inhibitors; D014452:Ubiquitins; D000255:Adenosine Triphosphate; D047390:Casein Kinase II; D017346:Protein Serine-Threonine Kinases; D010447:Peptide Hydrolases; D046988:Proteasome Endopeptidase Complex; C061553:ATP dependent 26S protease; D000623:Porphobilinogen Synthase