Protein kinase activity in meristematic root tips of Pisum sativum during germination

Abstract

Membranes isolated from pea root meristems contain a protein kinase activity and a number of unidentified endogenous substrates. The enzyme activity increases in presence of MgCl 2 and MnCl 2 but not in presence of CaCl 2; the maximum of phosphorylation activity has been observed after 45 s of incubation. This protein kinase activity is partially solubilized by Triton X-100, although no extensive purification has been attempted. The activity falls during the first hours of germination and is detected only in membranes obtained from meristematic tissues. In the same membrane system, protein phosphatase activity could be present; if this data is confirmed then an interesting mechanism of phospho-dephosphorylation of proteins could exist in pea root meristematic membranes. In this case, such a particular membrane system could become very useful for investigating the physiological role of phosphorylations of protein membrane components during cell proliferation and germination.