Abstract
The docking/fusion of transport vesicles mediated by the SNARE proteins is thought to be regulated by Sec1/Munc-18 (SM) proteins, but their precise roles are still unclear. There are 6 SM protein encoding genes on the C. elegans genome, however, no systematic functional studies have yet been performed.
In this work, we focused on the Ce-vps45 whose orthologous protein in yeast plays an important role in vacuolar protein sorting. The putative null mutation, tm246, showed a maternal-effect ts larval lethal phenotype. The ts lethal phenotype of tm246 mutant was rescued when Ce-vps45 cDNA was speficically expressed in the intestine. This result suggest that Ce-vps45 gene products may function in membrane trafficking from Golgi's apparatus to lysosome in mainly intestinal cells where lysosome is highly developed. To visualize specific membrane trafficking pathway, transgenic analyses using fluorescent reporters in the mutant background are in progress.
In addition to disfunction of intracellular membrane trafficking, the mutant tm246 shows abnormal endocytotic uptake of proteins from pseudocoelom to coelomocytes. Both RME (receptor mediated endocytosis) and non-RME appeared to be impaired. We infer that the CE-VPS45 protein is necessary for both biosynthetic and endocytic membrane trafficking pathways. [Jpn J Physiol 54 Suppl:S78 (2004)]
