ARFs get the BioID treatment: what have we been missing?

Abstract

Li et al present the results of a proximity-interaction screen in mammalian cells for the effector proteins of 25 members of the Arf family of small GTPases. This study has generated an important resource for those working in several areas of cell biology and provided an initial characterisation of two new cellular roles for some of the least well studied members of this family, the regulation of PLD1 by ARL11/14 in phagocytosis, and the regulation of PI4KB by ARL5A/5B in the Golgi.

Figure 1. Proximity labelling reveals novel roles of Arf family GTPases

Proximity labelling was applied by Li et al (2022) to screen the proximal interactors of 25 members of the Arf family of small GTPases. Constitutively active mutants of each GTPase were fused to miniTurbo biotin ligase and stably expressed in HEK293 cells. The addition of biotin induces the biotinylation of proteins within nanometres of miniTurbo, allowing their quantification by LC–MS. Among the 1,667 hits obtained, two phospholipid signalling enzymes, PLD1 and PI4KB, were further explored, revealing novel roles for poorly described Arf‐like GTPases. ARL11 and ARL14 emerged as potent activators of PLD1, and ARL11 was found to stimulate phagocytosis via PLD1. ARL11/14 interaction involved a central loop region present in PLD1, but not PLD2, which might explain the selective modulation of PLD1 by Arf family GTPases. PI4KB was found to interact with ARL5A and ARL5B, contributing to PI4K recruitment to the trans‐Golgi network, for PI4P generation. GTP‐bound ARL5A/5B stimulated protein secretion in a PI4KB‐dependent manner, suggesting a role for these GTPases in regulating the secretory pathway.