Sterol regulatory element binding proteins(SREBPs)are nuclear transcription factors critical for regulating the expression of genes related to glucose and lipid metabolism.In order to investigate the molecular regulatory mechanisms of lipid metabolism and liver lipid accumulation in fish, the partial cDNA sequence of sterol regulatory element binding protein 1(SREBP-1)from grass carp has been identified by homology cloning and rapid amplification cDNA ends(RACE), and the structural features of the gene and its encoded protein have been analysed by bioinformatics methods.Using the method of real-time PCR, the expression pattern of SREBP-1 in eight different tissues of grass carp has been studied, and the expression levels of SREBP-1 in liver of grass carp under different feeding conditions with low-carbohydrates(carbohydrates content 24%)and high carbohydrates(carbohydrates content of 42%)have been studied.The result revealed that the obtained cDNA of SREBP-1 in grass carp is 4 760 bp in length, which consisted of a 3 426 bp open reading frame(ORF), encoding 1 141 amino acids.The amino acid sequence has a typical basic helix-loop-helix leucine zipper(bHLH-zip).Alignment based on amino acid sequence showed that grass carp SREBP-1 had a homology of 76%-88% to its counterparts of other fishes.Phylogenetic analysis showed that grass carp SREBP-1 clustered with that of zebrafish.The SREBP-1 mRNA could be detected in all the examined tissues of grass carp.But the expression level in brain was the highest, followed by liver and intestines, and with a little expression in the kidney, spleen, muscle, fat and gonad tissues.Compared with the control, the expression level of SREBP-1 in high carbohydrates(42%)induced group increased significantly(P<0.05).The results showed that SREBP-1 gene may promote the utilization and in version of carbohydrates in grass carp under high carbohydrates loading conditions, which suggested that it may improve the utilization of carbohydrates in grass carp and be involved in its carbohydrates metabolism process.The research data can enrich the glucose metabolism regulation mechanism of fish, and are expected to provide a theoretical basis for improving the utilization efficiency of sugar in fish feed.