|Budget Amount *help
¥2,500,000 (Direct Cost : ¥2,500,000)
Fiscal Year 2004 : ¥1,200,000 (Direct Cost : ¥1,200,000)
Fiscal Year 2003 : ¥1,300,000 (Direct Cost : ¥1,300,000)
VIP36,ERGIC53,VIPL, and ERGL are intracellular lectins possibly involved in intracellular transport of newly synthesized glycoproteins. Although VTP36 has been shown to be expressed in rat parotid gland, it remains unclear how VTP36 contributes to transport and secretion of salivary glycoproteins. In 2003,we found that there exists at least two density-distinct vesicles in rat parotid cells, and that in lighter ones, VIP36 and α-amylase containing high mannose-type glycan(s) are colocalized, while in heavier ones, only non-glycosylated α-amylase is present. Immunoprecipitation analysis showed the binding of α-amylase to VTP36 in the lighter vesicles. Endo-β-N-acetylglucosaminidase activities were detected in the both vesicle fractions. These results suggested a possibility ; i)newly synthesized, glycosylated a-amylase binds to VIP36,and the complex is accumulated in the lighter vesicles, ii)Removal of high mannose-type glycan(s) of α-amylase by endo-β-N-acetylglucosaminidase promotes dissociation of the complex, iii)Non-glycosylated α-amylase is deposited in the heavier vesicles and secreted. In 2004,we performed cDNA cloning of carbohydrate-binding regions of VTP36,ERGIC53,and VIPL, and prepared the recombinant proteins. By BIA-Core analysis, we showed that the proteins commonly recognize high mannose-type glycans.