IFT27 (intraflagellar transport 27) is a small GTPase-like component of the intraflagellar transport (IFT) complex B that functions primarily in ciliary protein trafficking and hedgehog signaling 1. IFT27 forms a functional dimer with IFT25 within the IFT-B complex, constituting the interface with the BBSome cargo adaptor complex 2. Mechanistically, IFT27 promotes BBSome exit from cilia through its interaction with ARL6 and prevents aggregation of GTP-free ARL6, while not participating in BBSome entry [UniProt reference]. The IFT25-IFT27 dimer binds the IFT74-IFT81 dimer of IFT-B in a manner mutually exclusive with RABL2 GTPase, regulating ciliary GPCR export including GPR161 and Smoothened 23. IFT27 is essential for male fertility, spermiogenesis, and sperm flagella formation, with particular importance in ciliated tissues [UniProt reference]. Disease relevance includes Bardet-Biedl syndrome (BBS19), where IFT27 mutations impair cooperation with IFT74-IFT81, causing ciliary defects 3. IFT27 mutations also cause retinitis pigmentosa through impaired photoreceptor outer segment maintenance via hedgehog pathway disruption 4, and complete loss causes fetal lethal ciliopathy with altered ciliogenesis 5.