Downstream effector for Rab11 which regulates Rab11 intracellular membrane trafficking functions such as endocytic recycling, intracellular ciliogenesis and protein export (PubMed:31204173, PubMed:32344433). ATK1-mediated phosphorylation of WDR44 induces binding to Rab11 which activates endocytic recycling of transferrin receptor back to the plasma membrane (PubMed:31204173). When bound to Rab11, prevents the formation of the ciliogenic Rab11- Rabin8/RAB3IP-RAB11FIP3 complex, therefore inhibiting preciliary trafficking and ciliogenesis (PubMed:31204173). Participates in neo- synthesized protein export by connecting the endoplasmic reticulum (ER) with the endosomal tubule via direct interactions with the integral ER proteins VAPA or VAPB and the endosomal protein GRAFs (GRAF1/ARHGAP26 or GRAF2/ARHGAP10), which facilitates the transfer of proteins such as E-cadherin, MPP14 and CFTR into a Rab8-Rab10-Rab11-dependent export route (PubMed:32344433). {ECO:0000269|PubMed:31204173, ECO:0000269|PubMed:32344433}. This is the function of WDR44 (WD repeat domain 44, Ensembl gene identifier ENSG00000131725).