Blumenthal, Donald K.; Wangsgard, Wendy P.; Meixell, Glenn E.
Activation and inhibition of phosphorylase kinase by monospecific antibodies raised against peptides from the regulatory domain of the gamma-subunit.
The C terminus of the catalytic gamma-subunit of phosphorylase kinase comprises a regulatory domain that contains regions important for subunit interactions and autoinhibitory functions. Monospecific antibodies raised against four synthetic peptides from this region, PhK1 (362-386), PhK5 (342-366), PhK9 (322-346), and PhK13 (302-326), were found to have significant effects on the catalytic activities of phosphorylase kinase holoenzyme and the gamma delta complex. Antibodies raised against the very C terminus of the gamma-subunit, anti-PhK1 and anti-PhK5, markedly activated both holoenzyme and the gamma delta complex, in the presence and absence of Ca2+. In the presence of Ca2+ at pH 8.2, anti-PhK1 activated the holoenzyme more than 11-fold and activated the gamma delta complex 2.5-fold. Activation of the holoenzyme and the gamma delta complex by anti-PhK5 was 50-70% of that observed with anti-PhK1. Prior phosphorylation of the holoenzyme by the cAMP-dependent protein kinase blocked activation by both anti-PhK1 and anti-PhK5. Antibodies raised against the peptides from the N terminus of the regulatory domain, anti-PhK9 and anti-PhK13, were inhibitory, with their greatest effects on the gamma delta complex. These data demonstrate that the binding of antibodies to specific regions within the regulatory domain of the gamma-subunit can augment or inhibit structural changes and subunit interactions important in regulating phosphorylase kinase activity.
American Society for Biochemistry and Molecular Biology (ASBMB)
Wangsgard WP, Meixell GE, Dasgupta M, Blumenthal DK. Activation and inhibition of phosphorylase kinase by monospecific antibodies raised against peptides from the regulatory domain of the gamma-subunit. J Biol Chem. 1996 Aug 30;271(35):21126-33. Retrieved September 14, 2006 from ttp://www.jbc.org/cgi/content/full/271/35/21126