Related Experiment Video
Updated: Jul 11, 2026

Heterokaryon Technique for Analysis of Cell Type-specific Localization
Published on: March 11, 2011
Nuclear redirection of a cytoplasmic helix-loop-helix protein via heterodimerization with a nuclear localizing
1Institute of Pathology, Case Western Reserve University, Cleveland, Ohio 44106.
Abstract:
The DNA-binding basic domain of helix-loop-helix transcriptional (HLH) factors in several instances also serves as a nuclear localization signal (NLS). Interestingly, some members of the HLH family of proteins lack a basic domain or any other recognizable NLS and yet still display efficient nuclear localization. To study this apparent paradox, we used the hematopoietic HLH protein SCL/tal as a model. Deletion of the basic domain converted SCL/tal from nuclear to a cytoplasmic protein. However, the basic domain deficient SCL/tal protein could be redirected to the nucleus by coexpression of E2-5, an SCL/tal-binding HLH protein with an intact basic domain. These results indicate that heterodimerization of HLH proteins may take place in the cytoplasm prior to nuclear localization and that nuclear localization for HLH complexes is a dominant process requiring only a single NLS per complex.
More Related Videos
10:03Isolation of CA1 Nuclear Enriched Fractions from Hippocampal Slices to Study Activity-dependent Nuclear Import of Synapto-nuclear Messenger Proteins
Published on: August 10, 2014
10:05Visualization of Protein-protein Interaction in Nuclear and Cytoplasmic Fractions by Co-immunoprecipitation and In Situ Proximity Ligation Assay
Published on: January 16, 2017
Related Concept Videos
Nuclear Export of mRNA
Nuclear Protein Sorting
Proteins targeted to the nucleus carry nuclear localization signals or NLS recognized by import receptors in the cytosol. Similarly, proteins with nuclear export signals are recognized by export receptors. Import and export receptors are...
Nuclear Localization Signals and Import
Nuclear Export
NES are of three types- the canonical 10-residue long leucine-rich signal and other...
Directionality of Nuclear Transport
Regulation of Nuclear Protein Sorting