| Budget Amount *help |
¥3,600,000 (Direct Cost: ¥3,600,000)
Fiscal Year 2004: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2003: ¥2,000,000 (Direct Cost: ¥2,000,000)
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| Research Abstract |
To understand detailed mechanisms of the transport of lysosomal enzymes, clathrin adopter proteins, the GGAs and AP1, and the mannose 6-phosphate receptor (MPR) were fused with GFP, which were examined by live-cell imaging and FRAP (fluorescence recovery after photobleaching) analysis. Through this research project, following results were obtained.
1. GGA1 and AP1 showed different distribution patterns in the TGN (trans-Golgi network) region, and most transport carriers that left the TGN contained AP1 alone. These results suggest that GGAs and AP1 are involved in the pre- and post-budding events, respectively.
2. GGA2 repeated association and motion with the TGN membrane more rapidly than GGA1 and GGA3. Moreover, the presence of the hinge-ear domain of GGA1 retarded this cycling kinetics.
3. The presence of the extracellular domain of the cation-independent MPR may facilitate the fusion of the TGN-derived transport carvers containing the MPR with endosomes, and retain the MPR in the peripheral region for longer periods.
Followings are results obtained in relation to this research project.
1. A splice-variant of GGA3 was predominantly expressed in several human tissues except brain, and human-derived culture cell lines. Because the variant form lacks a binding site for MPR, GGA3 may play a new role other than the MPR trafficking.
2. U18666A treatment caused an accumulation of MPR in aberrant endosomal structures. This redistribution may associate with ligand-dependent transport steps of MPR.
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