Abstract
Chlamydomonas reinhardtii secretes arylsulfatase (ARS) to the periplasmic space in response to sulfate starvation. We have shown that the ARS transport is mediated by a mechanism similar to that observed in mammalian cells.
In this report, we studied the ARS secretion site by immunofluorescence using anti-ARS antibodies. Cells cultured in the sulfate-free medium had bright signals in a periplasmic region adjacent to the basal body, while control cells or oryzalin treated cells did not. This result suggests that ARS is transported by the microtubule-dependent polarized transport mechanism. To study effects of protein factors, we cloned a SAR1 homolog gene which encodes a GTP-binding protein required for the vesicle formation from the ER, and also constructed a dominant-negative version of the SAR1 gene.
We are doing the ultrastructural analysis of effects of reagents and the mutant SAR1 on the morphology of transported vesicles and organelle (Golgi and ER).
