ADP-ribosylation factors

Analysis of ARF Gene Family between Model and Crop

The functional organization of eukaryotic cells requires the exchange of proteins, lipids, and polysaccharides between membrane compartments through transport intermediates. Transport from one compartment of this pathway to another is mediated by vesicular carriers. The activation of small GTPases is essential for vesicle formation from a donor membrane (Keskin, 2013). Over the evolution of eukaryotic organisms, the conservation of GTPases implies their significance in cellular signaling processes (Inoue and Randazzo, 2007). ADP-ribosylation factors (ARFs) belong to the Ras-related small GTPases binding proteins and comprise the largest family of signaling proteins which modulate vesicle mediated transport (D’Souza-Schorey and Chavrier, 2006). The function of ARFs is highly regulated by their recycling between GTP–bound active conformation and GDP-bound inactive conformations (Lee et al., 2005). Inactive GDP-bound ARFs may be recruited from cytosol onto the membrane by interacting with receptor proteins, and their association with the membrane is mediated through the N-terminal myristoylated amphipathic helix domain. On the membrane, ARFs undergo the exchange of GDP for GTP, which is catalyzed by guanine nucleotide exchange factors (GEFs). As with other GTPases, GTP–bound active ARFs induces a conformational change that allows them to interact with a variety of effector proteins, including coat proteins such as the COPI complex, clathrin adaptor protein complexes, phospholipase D, and phosphatidylinositol 4-kinase (Nakai et al., 2013). The ARF proteins are highly conserved among species from yeast to mammals as well as in plants and are classified based on amino acid sequence homology. The mammalian ARF family consists of six gene family that is divided into three classes based on the sequence homology. Class I includes ARF1, ARF2 and ARF3, class II ARF4 and ARF5, and class III ARF6. ARF Classes I and II localize to the Golgi and endoplasmic reticulum, and primarily regulate vesicular trafficking between these organelles. In contrast, Arf6 predominantly localizes to the plasma membrane and endosomal compartments. (D’Souza-Schorey and Chavrier,2006). In the present study, we performed in silico analysis on the diversity of ARF family proteins in model and crop plants. The analysis revealed that ARF family proteins were evolutionary conserved in model and crop plants. However, the number of ARFs family proteins increased in Group I compare to other ARF family protein groups. Our results suggest that Group I ARFs might play more crucial role during crop breeding history.