Isolation and Characterization of a Dual Prenylated Rab and VAMP2 Receptor

Abstract

Rab GTPases have been implicated in intracellular vesicle trafficking. Using the yeast two-hybrid screen, we have isolated a rat clone that interacts with Rab3A as well as with Rab1. The gene encodes a 20.6-kDa protein with two extensive hydrophobic domains and is broadly expressed in all tissues. This protein binds to prenylated Rab GTPases but not to other small Ras-like GTPases such as the Rho/Rac family. This prenylated Rab acceptor (PRA1) also binds specifically to the synaptic vesicle protein VAMP2 (or synaptobrevin II) but shows no affinity for VAMP1 or cellubrevin in both the yeast twohybrid system and in vitro binding assays. This specificity resides, in part, in the proline-rich domain of VAMP2 as a chimera containing this domain of VAMP2 fused to VAMP1 is able to bind to PRA1. The transmembrane domain of VAMP2 is also essential as its deletion abolished binding to PRA1. Replacement of the deleted VAMP2 transmembrane domain by a CAAX prenylation signal can not restore binding to PRA1. This interaction is therefore distinct from that required for VAMP2 binding to either syntaxin or both syntaxin and SNAP-25. Deletion analysis on PRA1 indicates that the critical Rab-and VAMP2-interacting residues reside in two regions: the amino-terminal residues 30 -54 and the extreme carboxyl-terminal domain. This dual Rab and VAMP2 binding characteristic suggests that PRA1 may serve to link these two protein families in the control of vesicle docking and fusion.

Expression of rTSβ as a 5-fluorouracil resistance marker in patients with primary breast cancer

“…These observations supported our results, and clearly provided an explanation as to how FTIs affect cell growth in addition to p53 (33,34). However, since no canonical CAAX sequence, a protein farnesylation signal (37), was identified at the C-terminus of rTSß, we are less certain that nuclear rTSß follows the traditional farnesylation process (37)(38)(39). Therefore, besides a quantitative difference in gene expression, qualitative change and different organelle localization of the individual gene product may also play an important role in determining the pathological activities of malignant cells, which in turn affects drug sensitivity and prognosis of the patients.…”

ThePRA1Gene Family in Arabidopsis

“…Regarding the spatial distribution, PRA1 homologs have been ubiquitously found in human tissues, emphasizing their importance for development (Martincic et al, 1997;Abdul-Ghani et al, 2001;Bucci et al, 2001;Schweneker et al, 2005;Fo et al, 2006). Based on our results in 8-d-old seedlings, AtPRA1 transcripts are differently distributed, mainly accumulating in emerging organs and vascular tissues.…”

“…In chemical synapses, PRA1 associates with Piccolo, a zinc finger protein of the presynaptic cytoskeletal matrix, suggesting a function in synaptic vesicle trafficking (Fenster et al, 2000). PRA1 also interacts with other prenylated small GTPases, such as the mouse Ha-Ras, N-Ras, TC21, and RhoA, as well as with the v-SNARE protein VAMP2 (Martincic et al, 1997;Figueroa et al, 2001), and it plays a role as modulator of the neural Glu transporter excitatory amino acid carrier 1 (Akiduki et al, 2007). Because of its capacity to interact with GTPases and SNARE proteins, PRA1 might connect these two large groups of proteins to efficiently control vesicle docking and fusion events.…”

The Yip1p·Yif1p Complex Is Required for the Fusion Competence of Endoplasmic Reticulum-derived Vesicles

“…It has been suggested that Pra1p is a GDI displacement factor that recruits Rab3A to membranes (40). In addition to binding to Rabs, Pra1p binds to the SNARE Vamp2p (39). Although Pra1p localizes predominantly to Golgi membranes (41), it is also present at the presynaptic active zone where it is a component of the cytoskeletal matrix.…”