Cyclic AMP Receptor Protein of E. coli: Its Role in the Synthesis of Inducible Enzymes
Abstract
A cyclic AMP binding protein has been purified over 100-fold from E. coli extracts. Protein purified from wild-type strains binds cyclic AMP with an apparent dissociation constant of 1-2 × 10-6 M. Two mutant strains that are unresponsive to exogenous cyclic AMP have altered binding activity; the protein purified from one of these mutants has a decreased affinity for cyclic AMP (apparent dissociation constant = 2 × 10-5 M). Extracts of this mutant are deficient in their ability to support β-galactosidase synthesis in vitro. The addition of purified, wild-type binding protein to these extracts restores enzyme synthesis toward normal. Because this binding protein appears to be required for cyclic AMP action, we suggest it be called the cyclic AMP receptor protein (CR protein).
Footnotes
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↵ * Diabetes Section, Clinical Endocrinology Branch, National Institute of Arthritis and Metabolic Diseases, National Institutes of Health, Bethesda, Md. 20014.
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↵ † Molecular Biology Section, Endocrinology Branch, National Cancer Institute, National Institutes of Health, Bethesda, Md. 20014. Requests for reprints should be sent to Dr. Pastan, Building 10, Room 10B09 of this address.
