Comparison of phosphorylation of elongation factor 1 from different species by caScin kinase II

Abstract
One subunit of EF-1 or EF-1/βγ from Artemia salina, wheat germ and rabbit reticulocytes is modified by caScin kinase II. The subunit corresponds to the low Mr, subunit of EF-1 (26000–36000) which functions along with a higher Mi subunit (46000–48000). to catalyze the exchange of GDP for GTP on EF-1α. The factor from Artemia and wheat germ is phosphorylated directly on serine by casein kinase II whereas a modulatory compound is required for phosphorylation of EF-1 from reticulocytes. Polylysine increases the rate of phosphorylation of EF-1 from reticulocytes by 24-fold: both serine and threonine arc modified. This suggests that polylysinc may be substituting for a physiological regulatory compound which modulates phosphoryation in vivo