The Role of Ca2+ and Protein Phosphorylation in Glycerol Dissimilation under Hypoosmotic Stress in the Halotolerant Alga Dunaliella.

Abstract

The role of Ca2+ and protein phosphorylation in glycerol dissimilation under hypoosmotic stress in the halotorelant alga Dunaliella was investigated by a pharmacological approach. A stretch-activated Ca2+ channel blocker, GdCl3, inhibited glycerol dissimilation under hypoosmotic stress. Glycerol dissimilation under hypoosmotic stress was also inhibited in the presence of protein kinase inhibitors, K-252a and staurosporine. K-252a and staurosporine potently inhibits several types of protein kinase including serine/ threonine- and tyrosine-type protein kinases. Erbstatin analog (metyl 2, 5-dihydroxy-cinnamate), a specific inhibitor of tyrosine-type protein kinase, however, had no effect on glycerol dissimilation under hypoosmotic stress. The results of the present study suggest that Ca2+ influx from the extracellular space and protein phosphorylation by K-252a- and staurosporine-sensitive protein kinase (s) appear to be participate in the process of glycerol dissimilation under hypoosmotic stress in Dunaliella.