The N-terminal region of ABC50 interacts with eukaryotic initiation factor eIF2 and is a target for regulatory phosphorylation by CK2

Biochem J. 2008 Jan 1;409(1):223-31. doi: 10.1042/BJ20070811.

Abstract

ABC50 is an ABC (ATP-binding cassette) protein which, unlike most ABC proteins, lacks membrane-spanning domains. ABC50 interacts with eIF2 (eukaryotic initiation factor 2), a protein that plays a key role in translation initiation and in its control, and in regulation of ribosomes. Here, we establish that the interaction of ABC50 with eIF2 involves features in the N-terminal domain of ABC50, the region of ABC50 that differs most markedly from other ABC proteins. This region also shows no apparent similarity to the eIF2-binding domains of other partners of eIF2. In contrast, the N-terminus of ABC50 cannot bind to ribosomes by itself, but it can in conjunction with one of the nucleotide-binding domains. We demonstrate that ABC50 is a phosphoprotein and is phosphorylated at two sites by CK2. These sites, Ser-109 and Ser-140, lie in the N-terminal part of ABC50 but are not required for the binding of ABC50 to eIF2. Expression of a mutant of ABC50 in which both sites are mutated to alanine markedly decreased the association of eIF2 with 80S ribosomal and polysomal fractions.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • ATP-Binding Cassette Transporters / chemistry
  • ATP-Binding Cassette Transporters / metabolism*
  • Alanine / chemistry
  • Binding Sites
  • Casein Kinase II / chemistry
  • Casein Kinase II / metabolism*
  • Cell Line
  • Escherichia coli / metabolism
  • Eukaryotic Initiation Factor-2 / chemistry
  • Eukaryotic Initiation Factor-2 / metabolism*
  • Humans
  • Phosphoamino Acids / metabolism
  • Phosphorylation
  • Plasmids / metabolism
  • Protein Binding
  • Protein Biosynthesis
  • Protein Structure, Tertiary
  • Serine / chemistry

Substances

  • ABCF1 protein, human
  • ATP-Binding Cassette Transporters
  • Eukaryotic Initiation Factor-2
  • Phosphoamino Acids
  • Serine
  • Casein Kinase II
  • Alanine