TEKT3 is a microtubule inner protein (MIP) that forms part of the dynein-decorated doublet microtubules (DMTs) in the axoneme of cilia and flagella. It forms filamentous polymers in the walls of ciliary and flagellar microtubules, contributing to the structural framework on which motile axonemes are built. UniProt annotates the protein as required for normal sperm mobility.

The protein belongs to the tektin family. Tektins are filament-forming proteins that coassemble with tubulins to form ciliary and flagellar microtubules. According to UniProt, Tektin-3 localises to the cytoskeleton of the cilium axoneme and the flagellum axoneme, and also to the outer membrane of the acrosome, a secretory vesicle. The human TEKT3 gene sits in the HGNC gene group Tektins, and orthologues are annotated in mouse and rat as Tekt3.

The NCBI Gene summary notes that the exact function of this gene was not established at the time of the RefSeq annotation, whereas the later UniProt entry assigns it a role as an axonemal microtubule inner protein. Researchers studying the TEKT3 gene or the TEKT3 protein typically do so in the context of ciliary and flagellar structure and sperm motility. The gene has also been listed under the alias FLJ32828.