Involved in synaptic functions in photoreceptor cells, the signal transduction in immune cells as a Src family kinase activator, endosome recycling, the uptake of bacteria and endocytosis, protein trafficking in sensory neurons and as lipid-binding chaperone with specificity for a diverse subset of myristoylated proteins. Specifically binds the myristoyl moiety of a subset of N-terminally myristoylated proteins and is required for their localization. Binds myristoylated GNAT1 and is required for G protein localization and trafficking in sensory neurons. Probably plays a role in trafficking proteins in photoreceptor cells. Plays important roles in mediating Src family kinase signals for the completion of cytokinesis via RAB11A. {ECO:0000269|PubMed:12496276, ECO:0000269|PubMed:14757743, ECO:0000269|PubMed:19381274, ECO:0000269|PubMed:21642972, ECO:0000269|PubMed:22085962, ECO:0000269|PubMed:23535298, ECO:0000305|PubMed:22960633}. This is the function of ENSG00000109103 (UNC119, unc-119 lipid binding chaperone).