Purification and characterization of protein IIIb, a mammalian brain phosphoprotein

J Biol Chem. 1982 Jun 10;257(11):6524-8.

Abstract

The phosphorylation of a 55,000-dalton protein (Protein IIIb) present in mammalian brain was previously shown to be increased by depolarizing agents in the presence of calcium, by cyclic nucleotides, and by appropriate neurotransmitters. We now report that Protein IIIb has been purified 660-fold to near homogeneity and partially characterized. The hydrodynamic properties of the purified protein indicate that it exists as an elongated monomer. cAMP-dependent protein kinase catalyzes the incorporation of 0.82 mol of phosphate into serine/mol of protein. The protein is heterogeneous in isoelectric focusing, exhibiting multiple forms with isoelectric points ranging in pH from 6.6 to 7.3.

Publication types

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

MeSH terms

  • Amino Acids / analysis
  • Animals
  • Brain Chemistry*
  • Cattle
  • Kinetics
  • Microbial Collagenase / metabolism
  • Molecular Weight
  • Nerve Tissue Proteins / isolation & purification*
  • Phosphoproteins / isolation & purification*
  • Phosphorylation
  • Rats

Substances

  • Amino Acids
  • Nerve Tissue Proteins
  • Phosphoproteins
  • Microbial Collagenase