| The protein kinase C (PKC) family is a group of serine/threonine kinases that transduce a variety of signals in signal transduction cascades. A large number of structure-function studies have provided valuable information on the regulatory domain regarding membrane binding and activation of conventional PKC isozymes. However, the mechanistic interplay of how the regulatory domain, mainly the C1a and C1b domains, contribute to membrane binding and activation is not fully understood for novel PKCs.;In order to assess the specific contributions of the C1a and C1b lipid binding domains, site directed mutagenesis was preformed on the C1a and C1b domains of PKC-delta and PKC-epsilon. Our results indicated that residues in the C1a domain of PKC-delta had a more important role in lipid binding and activation than those found in the C1b domain. Conserved hydrophobic and cationic residues in the C1a and in the C1b domains of PKC-epsilon had a similar contribution to lipid binding and activation. These results give insight to the differential mechanisms of membrane binding and activation of PKC-delta and PKC-epsilon;Annexins are calcium and anionic lipid dependent proteins involved in membrane trafficking. We preformed several biophysical techniques to monitor the diffusion as well as protein aggregation of annexin I and its N-terminal region fused to the green fluorescent protein. Our results demonstrated that annexin I diffused, as a trimeric unit on the surface of vesicles while the N-terminus region did not show protein aggregation under the same conditions. |
