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Structural distinction between soluble and particulate protein kinase C species
D S Lester1, N Orr, V Brumfeld
1Department of Membrane Research, Weizmann Institute of Science, Rehovot, Israel.
Journal of Protein Chemistry
|April 1, 1990
Summary
This study reveals distinct structural and biochemical differences between soluble and particulate forms of protein kinase C. These variations explain the enzyme's differential localization and may apply to other regulatory enzymes.
Area of Science:
- Biochemistry
- Molecular Biology
- Cell Biology
Background:
- Peripheral membrane proteins, including regulatory enzymes, exhibit differential localization between soluble and particulate cellular fractions.
- Protein kinase C (PKC), a Ca2+/phospholipid-dependent enzyme, is one such protein with known dual localization.
Purpose of the Study:
- To investigate the biochemical and biophysical properties of soluble and particulate forms of protein kinase C.
- To elucidate the structural basis for the differential localization of PKC.
Main Methods:
- Purification of soluble and particulate PKC forms.
- Biochemical assays for enzyme activation.
- Spectroscopic techniques including far UV-circular dichroism and Fourier transform infrared spectroscopy.
- Fluorescence probe analysis to assess hydrophobicity and lipid association.
Main Results:
- Particulate PKC exhibited lower phospholipid requirements for activation compared to the soluble form.
- Particulate PKC displayed increased hydrophobicity and a higher alpha-helical content.
- Specific lipid spectra were associated with soluble PKC, while particulate PKC showed greater, less mobile lipid association.
Conclusions:
- Significant structural and biochemical differences exist between soluble and particulate PKC isoforms.
- These differences provide a molecular explanation for PKC's preferential localization.
- The findings may offer insights into the localization mechanisms of other membrane-associated regulatory enzymes.