As 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 involved in cilia function and/or assembly (PubMed:20889716, PubMed:36775821). Essential for functional IFT-A assembly and ciliary entry of GPCRs (PubMed:20889716, PubMed:36775821). Associates with the BBSome complex to mediate ciliary transport (By similarity). {ECO:0000250|UniProtKB:Q3UGF1, ECO:0000269|PubMed:20889716, ECO:0000269|PubMed:36775821}. This is the function of Ensembl gene identifier ENSG00000157796 (WDR19, WD repeat domain 19).