iPABP, an inducible poly(A)-binding protein detected in activated human T cells

Mol Cell Biol. 1995 Dec;15(12):6770-6. doi: 10.1128/MCB.15.12.6770.


The poly(A)-binding protein (PABP) binds to the poly(A) tail present at the 3' ends of most eukaryotic mRNAs. PABP is thought to play a role in both translation and mRNA stability. Here we describe the molecular cloning and characterization of an inducible PABP, iPABP, from a cDNA library prepared from activated T cells. iPABP shows 79% sequence identity to PABP at the amino acid level. The RNA binding domains of iPABP and PABP are nearly identical, while their C termini are more divergent. Like PABP, iPABP is primarily localized to the cytoplasm. iPABP is expressed at low levels in resting normal human T cells; following T-cell activation, however, iPABP mRNA levels are rapidly up-regulated. In contrast, PABP is constitutively expressed in both resting and activated T cells. iPABP mRNA was also expressed at much higher levels than PABP mRNA in heart and skeletal muscle tissue. These data suggest that the regulation of cytoplasmic poly(A)-binding activity is more complex than previously believed. In most tissues, poly(A)-binding activity is likely to be the result of the combined effects of constitutively expressed PABP and iPABP, whose expression is subject to more complex regulation.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Base Sequence
  • Binding Sites
  • DNA Primers
  • Gene Library
  • Humans
  • Lymphocyte Activation*
  • Molecular Sequence Data
  • Poly(A)-Binding Proteins
  • Polymerase Chain Reaction
  • Polyribonucleotides / metabolism
  • Protein Biosynthesis
  • RNA, Messenger / metabolism
  • RNA-Binding Proteins / biosynthesis*
  • RNA-Binding Proteins / chemistry
  • Sequence Homology, Amino Acid
  • Substrate Specificity
  • T-Lymphocytes / immunology
  • T-Lymphocytes / metabolism*


  • DNA Primers
  • Poly(A)-Binding Proteins
  • Polyribonucleotides
  • RNA, Messenger
  • RNA-Binding Proteins

Associated data

  • GENBANK/U33818