DYNLT3 encodes the Tctex-3 (T-complex testis-expressed protein 3) subunit of the cytoplasmic dynein motor complex[@kardon2003]. Like its close homolog DYNLT1 (Tctex-1), DYNLT3 functions as a light chain that contributes to the dynein motor assembly, powering minus-end-directed retrograde transport along microtubules[@vallee2004]. While DYNLT1 and DYNLT3 share structural homology and overlap in some functions, DYNLT3 has distinct expression patterns and cargo recognition properties, with particular enrichment in [neurons](/entities/neurons) and during early developmental stages. DYNLT3 has been implicated in spinal muscular atrophy, Huntington's disease, and certain forms of hereditary neuropathy[@pfister2005].
Structure
DYNLT3 adopts the characteristic Tctex-type beta-sandwich fold shared with DYNLT1 and other dynein light chain family members:
Core beta-sandwich: Two antiparallel beta-sheets form a compact globular domain approximately 12 kDa in size
Dimerization interface: The C-terminal region mediates homodimer formation, critical for dynein light chain assembly
Cargo recognition surface: The N-terminal region forms the interface for binding specific adaptor proteins and cargo complexes
DYNC1I binding domain: Associates with the dynein intermediate chain (DYNC1I1/DYNC1I2) to anchor into the dynein holoenzyme
The DYNLT3 homodimer assembles with the dynein heavy chain (DYNC1H1), light intermediate chain (DLIC1/2), and intermediate chain (DYNC1I1/2) to form a functional motor complex capable of generating force along microtubules[@makarova2000].
Normal Function
Retrograde Axonal Transport
DYNLT3-containing dynein complexes mediate retrograde transport of:
Signaling endosomes: Retrograde transport of neurotrophin receptors (TrkA, TrkB, p75NTR) from axon terminals to cell bodies
Mitochondria: Motility of mitochondria along axons for localized energy supply
Endocytic vesicles: Retrograde trafficking of recycling endosomes and synaptic vesicle precursors
Protein complexes: Transport of translational machinery and signaling complexes
Neuronal Development
During neuronal development, DYNLT3 plays roles in:
Trk receptor agonists: Activate TrkB/TrkA independently of retrograde transport
Key Publications
Kardon JR, Vale RD (2003). Regulators of the cytoplasmic dynein motor. Nat Rev Mol Cell Biol. PMID [12794922](https://pubmed.ncbi.nlm.nih.gov/12794922/)
Pfister KK et al. (2005). Genetic alterations of the dynein-dynactin complex in neurological diseases. J Cell Biol. PMID [16176982](https://pubmed.ncbi.nlm.nih.gov/16176982/)