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SWAP70, containing the DH domain, exhibited GEF activity toward the rice Rho GTPase OsRac1, and regulates chitin-induced production of reactive oxygen species and defense gene expression in rice[1].

Annotated Information


SWAP70 has been shown to exhibit GEF activities toward Cdc42, Rac, and Rho. In the present study, we found that rice [Oryza sativa (Os)] SWAP70 interacted with OsRac1 and the DH domain exhibited GEF activity toward OsRac1 in vitro, evidence that plants possess a functional DH domain. In addition, OsSWAP70 regulates chitin-induced ROS production and defense gene expression in rice. Thus, it is likely that SWAP70 functions as a GEF for Rac/Rop GTPases in rice[2].


Figure 1.Visualization of OsSWAP70A and OsRac1 using bimolecular fluorescence complementation (BiFC) in transiently transfected rice protoplasts. Vn-OsRac1 and Vc-OsSWAP70A contain the N-terminal and C-terminal fragments, respectively, of Venus. Venus fluorescence indicates interaction between OsSWAP70A and OsRac1. The GUS protein was used as a negative control. Scale bar = 5 μm[2].

The interaction in vivo between OsSWAP70A and OsRac1 in rice protoplasts were analysed by a bimolecular fluorescence complementation (BiFC) assay (Figure 1). OsRac1 tagged with the N-terminal domain [amino acids (aa) 1–154] of Venus (Vn-OsRac1) and OsSWAP70A tagged with the C-terminal domain (aa 155–238) (OsSWAP70A-Vc) were co-expressed in rice protoplasts together with the control red fluorescent protein (RFP). The Venus fluorescence was detected at the plasma membrane, whereas RFP was observed throughout the cytoplasm. These results indicate that OsRac1 and OsSWAP70A interacted with each other at the plasma membrane[2].


Figure 2.Comparison of amino acid sequence between the PH domains of OsSWAP70A and human SWAP70[2]

SWAP70 protein possessed a PH domain at the N-terminus of the putative DH domain, a characteristic of human SWAP70 Rho GEF[3]. Both the putative PH and DH domains had 22% identity and 64% similarity to human SWAP70 (Figure 2,3)[2].

Figure 3.Alignment of the amino acid sequences of the DH domains of OsSWAP70A and human SWAP70[2]

The PH domain contained four basic amino acids conserved in the PH domains of animal SWAP70 proteins, which are critical for binding to phosphatidylinositol 3,4,5-triphosphate (PIP3) [4]. We also found an additional SWAP70 homologous gene (Os07g0138100) in rice by a BLAST search. Therefore, Os03g0666200 and Os07g0138100 were named OsSWAP70A and OsSWAP70B, respectively. OsSWAP70A and OsSWAP70B shared 64.2% identity (data not shown). A BLAST-based search for plant SWAP70 indicated that maize and sorghum have two genes, and there is one gene in Arabidopsis, Vitis vinifera, Ricinus communis, and Populus trichocarpa (Figure 4), suggesting that the SWAP70 homologs are conserved in the plant kingdom[2].

Figure 4.Phylogenetic tree of the SWAP70 family in plants. Accession numbers for plant SWAP70 genes are: Oryza sativa OsSWAP70A: AK102364; O. sativa OsSWAP70B: AK059496; Arabidopsis thaliana AtSWAP70: NP_850155; Vitis vinifera VvSWAP70: XP_002283267; Ricinus communis RcSWAP70: XP_002520368; Populus trichocarpa PtSWAP70: XP_002302134; Zea mays ZmSWAP70A: ACF87744; Z. mays ZmSWAP70B: NP_001151119; Sorghum bicolor SbSWAP70A: Sb01g012500; S. bicolor SbSWAP70B: Sb02g0026210[2].

Labs working on this gene

  • Department of Advanced Bioscience, Graduate School of Agriculture, Kinki University, 3327-204 Nakamachi, Nara 631-8505, Japan
  • Laboratory of Plant Molecular Genetics, Nara Institute of Science and Technology, 8916-5 Takayama, Ikoma 630-0192, Japan
  • Plant Disease Resistance Research Unit, Division of Plant Sciences, National Institute of Agrobiological Sciences, Kannondai 2-1-2, Tsukuba, Ibaraki 305-8602, Japan


  1. Yamaguchi K, Kawasaki T. Function of Arabidopsis SWAP70 GEF in immune response[J]. Plant signaling & behavior, 2012, 7(4): 465-468.
  2. 2.0 2.1 2.2 2.3 2.4 2.5 2.6 2.7 Yamaguchi K, Imai K, Akamatsu A, et al. SWAP70 functions as a Rac/Rop guanine nucleotide‐exchange factor in rice[J]. The Plant Journal, 2012, 70(3): 389-397.
  3. Shinohara M, Terada Y, Iwamatsu A, et al. SWAP-70 is a guanine-nucleotide-exchange factor that mediates signalling of membrane ruffling[J]. Nature, 2002, 416(6882): 759-763.
  4. Oka, T., Ihara, S. and Fukui, Y. (2007) Cooperation of DEF6 with activated Rac in regulating cell morphology. J. Biol. Chem. 282, 2011–2018.

Structured Information