Covalent modification of all members of human cullin family proteins by NEDD8.
Recently we found that NEDD8, a ubiquitin-like protein, was linked covalently to human cullin-4A (abbreviated Cul-4A) by a new ubiquitin-related pathway that is analogous to but distinct from the ligating system for SUMO1, another ubiquitin-like protein. However, it remained unknown whether the other five members of the family of human cullin/Cdc53 proteins are modified by NEDD8. Here we report that all Hs-Cul family proteins, such as Cul-1, Cul-2, Cul-3, Cul-4B, and Cul-5, in addition to Cul-4A, were modified by covalent attachment of NEDD8 in rabbit reticulocyte lysates. Moreover, by comprehensive Northern-blot analyses, we examined multiple tissue distributions of the messages for all Cul-family proteins, NEDD8, and the NEDD8-ligating system consisting of APP-BP1/hUba3, and hUbc12, which function as E1- and E2-like enzymes, respectively. The expressions of Cul-1, Cul-2, and Cul-3 resembled each other and were apparently correlated to those of NEDD8 and the NEDD8-ligating system in various human cells and tissues. However, the mRNA levels of Cul-4A, Cul-4B, and Cul-5 differed considerably from each other as well as from other Cul-family proteins. The enhanced expression of all Cul-family proteins except Cul-5 was observed in a variety of tumor cell lines.
Hori
T
T
Tokyo Metropolitan Institute of Medical Science, Japan.
Osaka
F
F
Chiba
T
T
Miyamoto
C
C
Okabayashi
K
K
Shimbara
N
N
Kato
S
S
Tanaka
K
K
D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D044842:Cullin Proteins; D005786:Gene Expression Regulation; D006801:Humans; D000075687:NEDD8 Protein; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014452:Ubiquitins / Q000235:genetics / Q000378:metabolism*
D018797:Cell Cycle Proteins; C100318:Cullin 1; D044842:Cullin Proteins; D000075687:NEDD8 Protein; C082860:NEDD8 protein, human; D012333:RNA, Messenger; D014452:Ubiquitins