Cloning and Sequence Analysis of Gene Encoding Plasma Membranes Intrinsic Protein of Stipa Grandis

Abstract

Plasma membranes intrinsic proteins (PIPs), a member of aquaporins, mediate water transport in many plant species. In this study, the PCR primers were constructed to correspond to the second and fifth transmembrane domains of PIPs in Hordeum vulgare. Using RT-PCR, 5′ RACE and 3′ RACE, a full-length cDNA of PIP-Type aquaporin Gene was isolated from cDNA prepared from S. grandis, named SgPIP1. The analysis of the sequence shows that the SgPIP1 cDNA consists of 991 bp, which includes a 15 bp 5′ noncoding region, followed by 870 bp of open reading frame encoding 289 amino acids, and finally, a 106 bp 3′ noncoding region. The analysis of the amino acid sequence reveals that SgPIP1 contains the MIP family sequence SGXHXNPAVT, the PIP family signature sequence GGGANXXXXGY and TGI/TNPARSI/FGAAI/VI/VF/YN. SgPIP1 exhibits six predicted transmembrane helices and possesses two sets of conserved NPA motifs, which may be involved in the recognition and transport of water molecules across the water channel. As compared to PIPs from the other plant species, SgPIP1 should be a member of PIP1 subfamily.