Configuration of PKCalpha-C2 Domain Bound to Mixed SOPC/SOPS Lipid Monolayers
X-ray reflectivity measurements are used to determine the configuration of the C2 domain of protein kinase C{alpha} (PKC{alpha}-C2) bound to a lipid monolayer of a 7:3 mixture of 1-stearoyl-2-oleoyl-sn-glycero-3-phosphocholine and 1-stearoyl-2-oleoyl-sn-glycero-3-phosphoserine supported on a buffered aqueous solution. The reflectivity is analyzed in terms of the known crystallographic structure of PKC{alpha}-C2 and a slab model representation of the lipid layer. The configuration of lipid-bound PKC{alpha}-C2 is described by two angles that define its orientation, {theta} = 35{sup o} {+-} 10{sup o} and {phi} = 210{sup o} {+-} 30{sup o}, and a penetration depth (=7.5 {+-} 2 {angstrom}) into the lipid layer. In this structure, the {beta}-sheets of PKC{alpha}-C2 are nearly perpendicular to the lipid layer and the domain penetrates into the headgroup region of the lipid layer, but not into the tailgroup region. This configuration of PKC{alpha}-C2 determined by our x-ray reflectivity is consistent with many previous findings, particularly mutational studies, and also provides what we believe is new molecular insight into the mechanism of PKC{alpha} enzyme activation. Our analysis method, which allows us to test all possible protein orientations, shows that our data cannot be explained by a protein that is orientated parallel to the membrane, as suggested by earlier work.
- Research Organization:
- Brookhaven National Lab. (BNL), Upton, NY (United States). National Synchrotron Light Source
- Sponsoring Organization:
- DOE - OFFICE OF SCIENCE
- DOE Contract Number:
- DE-AC02-98CH10886
- OSTI ID:
- 1019655
- Report Number(s):
- BNL-95501-2011-JA; BIOJAU; TRN: US201115%%295
- Journal Information:
- Biophysical Journal, Vol. 97, Issue 10; ISSN 0006-3495
- Country of Publication:
- United States
- Language:
- English
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