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A splice variant of RILP induces lysosomal clustering independent of dynein recruitment.

Marsman M, Jordens I, Rocha N, Kuijl C, Janssen L, Neefjes J

Division of Tumor Biology, The Netherlands Cancer Institute, Amsterdam 1066CX, The Netherlands.

The small GTPase Rab7 controls fusion and transport of late endocytic compartments. A critical mediator is the Rab7 effector RILP that recruits the minus-end dynein-dynactin motor complex to these compartments. We identified a natural occurring splice variant of RILP (RILPsv) lacking only 27 amino acids encoded by exon VII. Both variants bind Rab7, prolong its GTP-bound state, and induce clustering of late endocytic compartments. However, RILPsv does not recruit the dynein-dynactin complex, implicating exon VII in motor recruitment. Clustering might still occur via dimerization, since both RILP and RILPsv are able to form hetero- and homo-dimers. Moreover, both effectors compete for Rab7 binding but with different outcome for dynein-dynactin recruitment and transport. Hence, RILPsv provides an extra dimension to the control of vesicle fusion and transport by the small GTPase Rab7.

Published 2 May 2006 in Biochem Biophys Res Commun, 344(3): 747-56.
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