Role of acidic amino acids in peptide substrates of the beta-adrenergic receptor kinase and rhodopsin kinase

Biochemistry. 1991 May 28;30(21):5118-25. doi: 10.1021/bi00235a002.


The beta-adrenergic receptor kinase (beta-ARK) phosphorylates G protein coupled receptors in an agonist-dependent manner. Since the exact sites of receptor phosphorylation by beta-ARK are poorly defined, the identification of substrate amino acids that are critical to phosphorylation by the kinase are also unknown. In this study, a peptide whose sequence is present in a portion of the third intracellular loop region of the human platelet alpha 2-adrenergic receptor is shown to serve as a substrate for beta-ARK. Removal of the negatively charged amino acids surrounding a cluster of serines in this alpha 2-peptide resulted in a complete loss of phosphorylation by the kinase. A family of peptides was synthesized to further study the role of acidic amino acids in peptide substrates of beta-ARK. By kinetic analyses of the phosphorylation reactions, beta-ARK exhibited a marked preference for negatively charged amino acids localized to the NH2-terminal side of a serine or threonine residue. While there were no significant differences between glutamic and aspartic acid residues, serine-containing peptides were 4-fold better substrates than threonine. Comparing a variety of kinases, only rhodopsin kinase and casein kinase II exhibited significant phosphorylation of the acidic peptides. Unlike beta-ARK, RK preferred acid residues localized to the carboxyl-terminal side of the serine. A feature common to beta-ARK and RK was a much greater Km for peptide substrates as compared to that for intact receptor substrates.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Aspartic Acid
  • Cattle
  • Cerebral Cortex / enzymology
  • Cyclic AMP-Dependent Protein Kinases*
  • Eye Proteins*
  • G-Protein-Coupled Receptor Kinase 1
  • Glutamates
  • Molecular Sequence Data
  • Peptides / chemistry
  • Peptides / metabolism
  • Phosphorylation
  • Protein Kinases / metabolism*
  • Receptors, Adrenergic, beta / metabolism
  • Rhodopsin / metabolism
  • Structure-Activity Relationship
  • Substrate Specificity
  • beta-Adrenergic Receptor Kinases


  • Eye Proteins
  • Glutamates
  • Peptides
  • Receptors, Adrenergic, beta
  • Aspartic Acid
  • Rhodopsin
  • Protein Kinases
  • Cyclic AMP-Dependent Protein Kinases
  • G-Protein-Coupled Receptor Kinase 1
  • beta-Adrenergic Receptor Kinases