TY - JOUR
T1 - A novel protein specifically interacting with homer2 regulates ubiquitin-proteasome systems
AU - Ishibashi, Takamasa
AU - Ogawa, Sachie
AU - Hashiguchi, Yasuko
AU - Inoue, Yuriko
AU - Udo, Hiroshi
AU - Ohzono, Hiroshi
AU - Kato, Akihiko
AU - Minakami, Reiko
AU - Sugiyama, Hiroyuki
PY - 2005/5
Y1 - 2005/5
N2 - Homer family proteins are encoded by three genes, homer1, 2 and 3. Most of these proteins are expressed constitutively in nervous systems and accumulated in postsynaptic regions. However, the functional significance of these proteins, especially the significance of the distinction among the proteins encoded by homer1, 2 and 3, is still obscure. In the present study, we isolated a cDNA clone encoding a novel protein by two-hybrid system screening using the C-terminal half of Homer2b as the bait. This protein, termed 2B28, has 297 amino acid residues and contains three major domains: a UBA domain, a coiled-coil region, and a UBX domain. When expressed in HEK293T cells, 2B28 showed colocalization with uniquitin and enhanced the expression levels of IκB or Homer1a proteins, which are known to be degraded by proteasomes, indicating that 2B28 is involved in ubiquitin-proteasome functions. 2B28 specifically interacted and colocalized with Homer2 proteins, but not with Homer1 proteins. So far, we have identified no counterpart of 2B28 for Homer1 experimentally or in the protein databases. These results suggest that the specific interaction of 2B28 with Homer2 may play a role in regulation of protein degradation by ubiquitin-proteasome systems and that this function may be specific to Homer2 proteins among Homer family proteins.
AB - Homer family proteins are encoded by three genes, homer1, 2 and 3. Most of these proteins are expressed constitutively in nervous systems and accumulated in postsynaptic regions. However, the functional significance of these proteins, especially the significance of the distinction among the proteins encoded by homer1, 2 and 3, is still obscure. In the present study, we isolated a cDNA clone encoding a novel protein by two-hybrid system screening using the C-terminal half of Homer2b as the bait. This protein, termed 2B28, has 297 amino acid residues and contains three major domains: a UBA domain, a coiled-coil region, and a UBX domain. When expressed in HEK293T cells, 2B28 showed colocalization with uniquitin and enhanced the expression levels of IκB or Homer1a proteins, which are known to be degraded by proteasomes, indicating that 2B28 is involved in ubiquitin-proteasome functions. 2B28 specifically interacted and colocalized with Homer2 proteins, but not with Homer1 proteins. So far, we have identified no counterpart of 2B28 for Homer1 experimentally or in the protein databases. These results suggest that the specific interaction of 2B28 with Homer2 may play a role in regulation of protein degradation by ubiquitin-proteasome systems and that this function may be specific to Homer2 proteins among Homer family proteins.
KW - Homer
KW - Novel homer-binding protein
KW - Protein degradation
KW - Ub-proteasome related domains
KW - Ubiquitin
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U2 - 10.1093/jb/mvi074
DO - 10.1093/jb/mvi074
M3 - Article
C2 - 15944415
AN - SCOPUS:21044436011
SN - 0021-924X
VL - 137
SP - 617
EP - 623
JO - Journal of Biochemistry
JF - Journal of Biochemistry
IS - 5
ER -