Shahriar Saeedi, M.Sc. Biology 2000

Targeting of calcium calmodulin-dependent protein kinase II to membranes


Communication between neurons is mediated by the controlled release of neurotransmitters from small synaptic vesicles. Several proteins are involved in the regulation of neurotransmitter release. One such family of proteins is the calcium/calmodulin-dependent protein kinases. Calcium/calmodulin-dependent protein kinase II (CaMKII) is one of the most abundant members of this protein family. and is found in many tissues with specific isoforms usually predominating in certain tissues. CaMKII is found CO- purified with synaptic vesicles. The question of how CaMKII is attached to the synaptic vesicle is addressed in this thesis. It was hypothesized that CaMKII may interact with the phospholipid component of the vesicle membrane, which could mediate binding.

C-terminal deletion mutants of murine α-CaMKII were produced by PCR directional cloning and liposome-binding assays were performed on the purified proteins. Binding of murine α-CaMKII to several types of liposomes was not observed. Recent studies into targeting of this enzyme suggest a role for anchoring proteins. Murine α-CaMKII like the β isoform from rat muscle may interact with membranes through a putative non-kinase translation product (a putative anchoring protein), which encompasses amino acids 230-270 at N-terminal of the regulatory domain rather than through direct binding with phospholipids.