Use of Immunohistochemistry to Determine Expression of Rab5 Subfamily of GTPases in Mature and Developmental Brains

Rab GTPases are essentially molecular switches. They serve as master regulators in intracellular membrane trafficking from the formation and transport of vesicles at the originating organelle to its fusion to the membrane at the target organelle. Their functions are diversified and each has their specific subcellular location. Their expression may vary significantly in the same cell when the level of protein production is significantly different in different physiologic status. One of the best examples is the transition from fetal to mature status of cells. Expression and localization of Rab GTPases in mature and developing brains have not been well studied. Immunohistochemistry is an efficient way in the detection, semiquantitation, and localization of Rab GTPases in tissue sections. It is inexpensive and fast which allow efficient mass screening of many sections. In this chapter, we describe the immunohistochemical assay protocol for analyzing several Rab protein expressions of the Rab5 subfamily, including Rab5, Rab17, Rab22, and Rab31, in developmental (fetal) and mature human brains.