As a component of the IFT complex A (IFT-A), a complex required for retrograde ciliary transport and entry into cilia of G protein-coupled receptors (GPCRs), it is required in ciliogenesis and ciliary protein trafficking (PubMed:27932497, PubMed:29220510). Involved in cilia formation during neuronal patterning. Acts as a negative regulator of Shh signaling. Required to recruit TULP3 to primary cilia (By similarity). Component of the IFT complex A (IFT-A) complex (PubMed:20889716, PubMed:27932497). IFT-A complex is divided into a core subcomplex composed of IFT122:IFT140:WDR19 which is associated with TULP3 and a peripheral subcomplex composed of IFT43:WDR35:TTC21B (PubMed:27932497, PubMed:29220510). Interacts with IFT43:WDR35; the interaction connects the 2 IFT-A subcomplexes (PubMed:29220510). Interacts with IFTAP; the interaction associates IFTAP with IFT-A complex (PubMed:30476139). Localizes to photoreceptor connecting cilia. Expressed in many tissues. Predominant expression in testis and pituitary. Forms the trimeric core subcomplex IFT122:IFT140:WDR19 via the C-terminal region, whereas it interacts with IFT43:WDR35 via the N-terminal region containing the WD repeats. The disease is caused by variants affecting the gene represented in this entry.