20S proteasome from LMP7 knock out mice reveals altered proteolytic activities and cleavage site preferences.
20S proteasomes of tissues from LMP7 knock out mice which show reduced MHC class I restricted antigen presentation were analyzed with regard to their subunit composition, peptide hydrolyzing activity and their ability to cleave a synthetic 25-mer polypeptide. LMP7 deficiency results in an enhanced incorporation of subunit MB1 and in a 2-3.8-fold increase in Vmax for the Suc-LLVY-MCA hydrolyzing activity. Since LMP7 deficiency also affects the cleavage site preference of 20S proteasomes the reduced MHC class I antigen presentation of LMP7 knock out mice is most likely due to an impairment in peptide generation.
Stohwasser
R
R
Institut für Biochemie der Charité, Humboldt Universität, Berlin, Germany.
Kuckelkorn
U
U
Kraft
R
R
Kostka
S
S
Kloetzel
P M
PM
D000595:Amino Acid Sequence; D000818:Animals; D002851:Chromatography, High Pressure Liquid; D003546:Cysteine Endopeptidases / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D015180:Electrophoresis, Gel, Two-Dimensional; D015395:Histocompatibility Antigens Class I / Q000276:immunology; D015151:Immunoblotting; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D051379:Mice; D018345:Mice, Knockout; D008969:Molecular Sequence Data; D009097:Multienzyme Complexes / Q000737:chemistry* / Q000302:isolation & purification / Q000378:metabolism*; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D046988:Proteasome Endopeptidase Complex; D011487:Protein Conformation; D011506:Proteins / Q000235:genetics / Q000502:physiology*; D013154:Spleen / Q000201:enzymology; D013950:Thymus Gland / Q000201:enzymology; D014162:Transfection
D015395:Histocompatibility Antigens Class I; D009097:Multienzyme Complexes; D010455:Peptides; D011506:Proteins; D003546:Cysteine Endopeptidases; C077436:LMP7 protein; D046988:Proteasome Endopeptidase Complex