Figure 4. In vitro autonomous Ca²⁺–calmodulin-dependent protein kinase II activity is positively related to phosphorylation at Thr²⁸⁷.

Correlation between CaMKII phosphorylation at Thr²⁸⁷ and autonomous CaMKII activity from skeletal muscle samples taken before and during contractions (A; r² = 0.43, P < 0.05, n = 39) and from basal skeletal muscle extracts manipulated to differing levels of phosphorylation by incubation with differing amounts of Ca²⁺ and calmodulin (B; r² = 0.73, P < 0.05, n = 4). A representative immunoblot is shown.