Crustacean hyperglycemic hormone (CHH) is the most abundant and best studied member of the CHH/MIH/GIH neuropeptide hormone family. CHH plays a major role in controlling glucose levels in the hemolymph, and it also has significance in regulating molting, reproduction, and osmoregulation. In contrast, molt-inhibiting hormone (MIH) is responsible for maintaining animals in an intermolt stage. In this study, Liv-MIH-1 cDNA, which encodes a mature neuropeptide from the eyestalk of white shrimp, Litopenaeus vannamei
, was expressed in methylotrophic yeast ( Pichia pastoris
KM71) under the control of an alcohol oxidase promoter. Recombinant Liv-MIH-1 was secreted into the culture medium using the α-factor prepro-sequence without Glu-Ala repeats. The expectedprotein, which had an apparent molecular mass of 12.1 kDa, was detected by Tricine-SDS-PAGE analysis and confirmed by Western blot. Pure recombinant Liv- MIH-1 was obtained by affinity chromatography, and N-terminal sequence analysis confirmed expression of the protein. Biological assays for CHH and MIH activity were also performed. Purified recombinant Liv-MIH-1 showed the ability to elevate the glucose level of hemolymph ofL. vannamei
, but molting was unaffected. Since these results are in agreement with the high structural and phylogenetic similarity that has been observed between Liv-MIH-1 and other CHH neuropeptides we propose to rename the protein Liv-CHH-SG1.