| Budget Amount *help |
¥3,500,000 (Direct Cost: ¥3,500,000)
Fiscal Year 2006: ¥1,200,000 (Direct Cost: ¥1,200,000)
Fiscal Year 2005: ¥2,300,000 (Direct Cost: ¥2,300,000)
|
|---|
| Research Abstract |
1) Characterization of GCP60 ; GCP60 was found to have a Golgi-localization signal at the C-terminal region (residue numbers 373-528), in which Tyr^<521> and Tyr^<522> were essential for the Golgi localization. In addition, The N-terminal residues Phe^<93> and Phe^<94> were found to act the exit signal from the endoplasmic reticulum (ER) to the Golgi. GCP60 contains a characteristic sequence similar with an acyl-CoA binding domain at the N-terminal region (104-164). As the acyl-CoA is reported to play a role for the ER-Golgi transport, we examined whether GCP60 has the acyl-CoA binding activity, in collaboration with Dr. N.Knudsen (Denmark). The result, however, showed that GCP60 has no acyl-CoA binding activity, even if the most sensitive assay method was used.
2) Characterization of GCP16 and GCP170 ; GCP16 was identified as a molecule interacting with GCP170, a member of the golgin family. GCP16 was found to be tightly associated with the Golgi membrane, although it has no transmembr
… More
ane domain. Labeling experiments [^3H]palmitate and mutational analysis demonstrated that GCP16 was acylated at Cys^<69>and Cys^<72>, accounting for its tight association with the membrane. A mutant without potential acylation sites was no longer localized to the Golgi, indicating that the acylation is prerequisite for the Golgi localization of GCP16 by interacting with GCP 170. In addition, it was found that GCP16 itself is a subunit of acyltransferase specific for the GTPase H-/N-ras, that was transported to the plasma membrane only after being acylated. On the other hand, when perforated cells were incubated with cytosol and ATP, the Golgi stack was disrupted into tubular structures. Under the condition GCP170 was rapidly released from the Golgi membrane. Such a structural change of the Golgi was recovered to the normal by addition of GCP170, indicating an important role of GCP170 in maintenance of the Golgi structure.
3) Interaction of p115 with the COG complex for maintenance of the Golgi structure ; p115, a tethering factor of COPI transport vedsicles, contains a highly homologous region (HR2) with the yeast Uso1p. The yeast two-hybrid screening revealed that HR2 domain of p115 interacts with Cog-2, a member of COG (Conserved Oligmeric Golgi) complex. When the p115 expression was knock-downed by siRNA, the Golgi complex was fragmented and disrupted. The expression of wild-type p115 recovered the normal Golgi structure in the affected cells, whereas the HR2-lacking p115 caused an abnormal irregular Golgi structure, suggesting that p115 interacts with COG complex and plays a role in maintenance of the Golgi structure. Less
|
