Expression and function analysis of Rac1 homolog in Chinese shrimp Fenneropenaeus chinensis.

Rac1 is a ubiquitous GTP-binding protein that plays a crucial role in multiple cellular processes. In the present study, a Rac1 homolog (FcRac1) was cloned from the Chinese shrimp Fenneropenaeus chinensis. The open reading frame (ORF) of FcRac1 consists of 579 bp encoding 192 aa. The predicted molecular weight (MW) of the deduced amino acid sequence of FcRac1 was 21.46 kDa, and its theoretical pI was 8.62. Homology analysis showed that the amino acid sequence of Rac1 had high conservation among those from different species. Phylogenetic analysis showed that FcRac1 closely related to Rac1 proteins from other arthropods. FcRac1 showed the highest expression level in the hemocytes. In situ hybridization detection showed that it distributed in all types of hemocytes. Recombinant protein of FcRac1 showed apparent activity of GTPase. The transcription of FcRac1 in juvenile shrimp changed after bacteria or WSSV challenge. The present data suggests that FcRac1 might play important roles in the innate immunity of shrimp.