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Studying Protein Function and the Role of Altered Protein Expression by Antibody Interference and Three-dimensional Reconstructions
Published on: April 21, 2016
A DnaJ protein, apobec-1-binding protein-2, modulates apolipoprotein B mRNA editing
P P Lau1, H Villanueva, K Kobayashi
1Department of Medicine, Baylor College of Medicine, Houston, Texas 77030, USA.
Apolipoprotein B mRNA editing complementation protein-2 (ABBP-2) is a DnaJ homologue that binds apolipoprotein B mRNA editing enzyme, catalytic polypeptide 1 (APOBEC1). ABBP-2 is essential for APOBEC1-mediated mRNA editing and influences protein localization.
Area of Science:
- Molecular biology
- Cell biology
- Biochemistry
Background:
- Mammalian DnaJ proteins, or Hsp40 proteins, function as co-chaperones with Hsp70.
- Apolipoprotein B (apoB) mRNA undergoes editing mediated by the apobec-1 (APOBEC1) enzyme.
- The precise mechanisms regulating APOBEC1 activity and localization are not fully understood.
Purpose of the Study:
- To identify and characterize novel proteins interacting with APOBEC1.
- To investigate the role of identified proteins in APOBEC1-mediated apoB mRNA editing.
- To elucidate the functional relationship between APOBEC1, DnaJ homologues, and Hsp70.
Main Methods:
- Yeast two-hybrid screening to identify APOBEC1-interacting proteins.
- Cloning and expression analysis of apobec-1-binding protein-2 (ABBP-2).
- Cell transfection studies to determine subcellular localization and functional assays to assess mRNA editing activity.
Main Results:
- ABBP-2, a Class II DnaJ homologue, was identified as an APOBEC1-binding protein.
- ABBP-2 is ubiquitously expressed and predominantly localized in the nucleus.
- Down-regulation of ABBP-2 inhibits APOBEC1-mediated apoB mRNA editing, which requires Hsp70 and ABBP-2 interaction.
- ABBP-2 lacks RNA recognition motifs, distinguishing it from other APOBEC1 auxiliary proteins.
Conclusions:
- ABBP-2 is a crucial co-factor for APOBEC1-mediated apoB mRNA editing.
- ABBP-2's interaction with Hsp70 is vital for editing activity.
- ABBP-2 may regulate APOBEC1's subcellular distribution and trafficking through Hsp70 interaction.
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