InterPro domain: IPR038586

Tctex-1 is a dynein light chain. Dynein translocates rhodopsin-bearing vesicles along microtubules and it has been shown that Tctex-1 can bind to the cytoplasmic tail of rhodopsin for retrograde or apical transport [ 1 ]. An efficient vectorial transport system must be required to deliver large numbers of newly synthesised rhodopsin molecules (~10 ⁷ molecules per day per photoreceptor) to the base of the outer segment of the photoreceptor, Tctex-1 may well play a role in this process. C-terminal rhodopsin mutations responsible for retinitis pigmentosa inhibit the interaction between Tctex-1 and rhodopsin, which may be the molecular basis of retinitis pigmentosa [ 2 ].

In the mouse, the chromosomal location and pattern of expression of Tctex-1 make it a candidate for involvement in male sterility [ 3 ].

This entry also includes Topoisomerase I damage affected protein 2 (TDA2) whose crystal structure revealed that it belongs to the dynein light chain family. It is part of the endocytic machinery and required for normal internalisation of native cargo in yeast [ 4 ].

1. Crystal structure of dynein light chain TcTex-1. J. Biol. Chem. 280, 21981-6
2. Rhodopsin's carboxy-terminal cytoplasmic tail acts as a membrane receptor for cytoplasmic dynein by binding to the dynein light chain Tctex-1. Cell 97, 877-87
3. tctex-1: a candidate gene family for a mouse t complex sterility locus. Cell 58, 969-79
4. Novel function of a dynein light chain in actin assembly during clathrin-mediated endocytosis. J Cell Biol 216, 2565-2580