SPIN90, an adaptor protein, alters the proximity between Rab5 and Gapex5 and facilitates Rab5 activation during EGF endocytosis

Abstract

Intracellular transport: a new SPIN A key protein required for incorporating substances into cells has been identified by researchers in South Korea. During this process, called endocytosis, materials are engulfed by the cell membrane, then packaged into vesicles by organelles called endosomes for transport around the cell. The small enzyme Rab5 is involved in fusing and transporting vesicles through interactions with a protein called Gapex5. It has been unclear how these interactions occur, but Woo Keun Song and Yun Hyun Huh at Gwangju Institute of Science and Technology and co-workers suspected a role for SPIN90, an ‘adapter protein’ that helps connect other molecules. They found that Rab5 and Gapex5 did not come close in mutant cells lacking SPIN90. In normal cells, SPIN90 interacted strongly with both Rab5 and Gapex5, recruiting them to endosomes where they operated together on vesicle formation.