Huntingtin is ubiquitinated and interacts with a specific ubiquitin-conjugating enzyme.
Using the yeast two-hybrid system, we have identified a human ubiquitin-conjugating enzyme (hE2-25K) as a protein that interacts with the gene product for Huntington disease (HD) (Huntingtin). This protein has complete amino acid identity with the bovine E2-25K protein and has striking similarity to the UBC-1, -4 and -5 enzymes of Saccharomyces cerevisiae. This protein is highly expressed in brain and a slightly larger protein recognized by an anti-E2-25K polyclonal antibody is selectively expressed in brain regions affected in HD. The huntingtin-E2-25K interaction is not obviously modulated by CAG length. We also demonstrate that huntingtin is ubiquitinated. These findings have implications for the regulated catabolism of the gene product for HD.
Kalchman
M A
MA
Department of Medical Genetics, University of British Columbia, Vancouver, British Columbia, Canada V6T 1Z4.
Graham
R K
RK
Xia
G
G
Koide
H B
HB
Hodgson
J G
JG
Graham
K C
KC
Goldberg
Y P
YP
Gietz
R D
RD
Pickart
C M
CM
Hayden
M R
MR
D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001921:Brain / Q000201:enzymology; D002417:Cattle; D002874:Chromosome Mapping; D002894:Chromosomes, Human, Pair 4; D018076:DNA, Complementary; D006801:Humans; D000071058:Huntingtin Protein; D008025:Ligases / Q000235:genetics / Q000378:metabolism*; D008969:Molecular Sequence Data; D009419:Nerve Tissue Proteins / Q000235:genetics / Q000378:metabolism*; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics; D044763:Ubiquitin-Conjugating Enzymes; D014452:Ubiquitins / Q000378:metabolism*
D018076:DNA, Complementary; C086055:HTT protein, human; D000071058:Huntingtin Protein; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D014452:Ubiquitins; C100879:UBE2K protein, human; D044763:Ubiquitin-Conjugating Enzymes; D008025:Ligases