Protein Kinase C ?: System of Modular Domains.

Signaling proteins comprised of modular domains have evolved along with multi-cellularity as a method to facilitate increasing intra-cellular bandwidth. The effects of intra-molecular interactions between modular domains, within the context of native proteins, have been largely unexplored. Here we examine intra- and inter-molecular interactions in the multi-domain signaling protein, protein kinase C α (PKCα). We identify three circumstances in which domain-domain interactions regulate PKCα function. First, we find that an intramolecular interaction between regulatory domains and the kinase domain limit catalytic function of PKCα as anticipated from previous studies. Second, we identify an intramolecular interaction between the C1a and C2 domain of PKCα that regulates self-assembly upon calcium binding. Third, we demonstrate that the intramolecular interaction between regulatory domains and the kinase domain facilitates heterologous growth of PKCα self-assembly upon calcium binding through ring opening polymerization. This dissertation proposes that PKCα is a system comprised of protein domain modules. We provide evidence that a network of domain-domain interactions regulate the function of PKC. Further, we provide evidence that upon binding known effectors the network of domain-domain interactions update and the function of PKCα changes. Together, this work hypothesizes that PKCα function in disparate biological phenomena can largely be attributed to internal domain-domain interactions. This work not only gives insight into PKC activation, but also provides a framework for regulatory mechanisms utilized by other kinase families and multi-domain proteins.PhDBiophysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttps://deepblue.lib.umich.edu/bitstream/2027.42/135936/1/cjswan_1.pd