Validation of species-specificity of two commercial antibodies directed against RILP (Rab-interacting lyosomal protein)

RILP is one of many effectors of RAB7 which bind to RAB7 in its activated GTP-bound state. The exact mechanism by which RAB7 effectors interact with RAB7 in time and space is not well understood. One of the known functions of RILP is to recruit dynein to RAB7-positive late endosomes. Dynein has been shown to be responsible for retrograde transport of RAB7-positive late endosomes in neuronal dendrites. We thus became interested in studying RILP in cultured neurons. We herein validate two commonly used anti-RILP antibodies which are commercially available. We find that both recognize only human RILP, but not mouse or rat RILP. These antibodies are thus not suitable for experiments carried out in mouse or rat cells. Furthermore, we find an unexpected difference between neurons and HEK293 cells in their ability to recruit overexpressed RILP to endosomes and cluster them in the cell center.