Abstract
The IGF family is essential for normal embryonic and postnatal development and plays important roles in the immune system, myogenesis, bone metabolism and other physiological functions, which makes the study of its structure and biological characteristics important. Tianzhu white yak (Bos grunniens) domesticated under alpine hypoxia environments, is well adapted to survive and grow against severe hypoxia and cold temperatures for extended periods. In this study, a full coding sequence of the IGF2 gene of Tianzhu white yak was amplified by reverse transcription PCR and rapid-amplification of cDNA ends (RACE) for the first time. The cDNA sequence revealed an open reading frame of 450 nucleotides, encoding a protein with 179 amino acids. Its expression in different tissues was also studied by Real time PCR. Phylogenetic tree analysis indicated that yak IGF2 was similar to Bos taurus, and 3D structure showed high similarity with the human IGF2. The putative full CDS of yak IGF2 was amplified by PCR in five tissues, and cDNA sequence analysis showed high homology to bovine IGF2. Moreover the super secondary structure prediction showed a similar 3D structure with human IGF2. Its conservation in sequence and structure has facilitated research on IGF2 and its physiological function in yak.
Highlights
Yak (Bos grunniens) is the most important animal species in the Tibet plateau because of its economic value in meat, milk, leather and velvet production [1], and as an ideal model animal for studying the adaption mechanisms in a cold, low oxygen environment
The deduced amino acid sequence of IGF2 was found to consist of an open reading frame of 179 amino acid residues (Figure 2)
The BLAST analysis for the coding region of yak IGF2 showed that it shared high similarity (100%–88%) with IGF2 from other mammals
Summary
Yak (Bos grunniens) is the most important animal species in the Tibet plateau because of its economic value in meat, milk, leather and velvet production [1], and as an ideal model animal for studying the adaption mechanisms in a cold, low oxygen environment. The insulin/IGF/relaxin superfamily is an ancient, functionally diverse protein family functioning in metabolism, growth and differentiation. Insulin-like growth factors (IGFs) are important members of the growth hormone-insulin-like growth factor-1 axis (GH-IGF1), and play important roles in fetal growth, development, proliferation, differentiation, apoptosis and transformation, especially in mammalian muscle [3,4] and cartilage cells [5]. IGFs contain the two best-characterized members, IGF1 and IGF2 [6]. Both of them, together with insulin, are members of a family of small proteins that show similarity at the levels of primary and tertiary structure, and some overlap in biological activities [7,8]. IGFs exert an anabolic effect in carbohydrate metabolism by stimulating glucose transport and glycogen deposition, and in protein metabolism by stimulating amino acids uptake, protein synthesis, and inhibiting proteolysis [10]
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