• Journal of Aquaculture
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• v.16 no.3
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• pp.165-170
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• 2003

Isolation, cloning and sequencing of red seabream (Pagrus major) somatolactin (rsbSL) cDNA from pituitary gland revealed an open reading frame of 693 bp coding for a pre-growth hormone of 231 amino acids with a 22 amino acid putative signal peptide. Deduced amino acid sequence showed that there was one possible N-glycosylation site at Asn$^{145}$ and seven Cys residues (Cys$_{29}$ , Cys$^{39}$ , Cys$^{66}$ , Cys$^{89}$ , Cys$^{205}$ , Cys$^{222}$ , Cys$^{230}$ ). Except Cys$^{66}$ , others may be involved in disulfide bond formation. The rsbSL presented a 93% amino acid sequence identity with the SL of gilthead seabream (Sparus aurata) and contained the conserved hormone domain region. Expression of rsbSL in E. coli (BL2l) cells and gel analysis revealed a higher molecular weight for rsbSL than expected theoretically, implying posttranslational modifications.

• Journal of Life Science
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• v.13 no.6
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• pp.805-813
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• 2003

cDNA encoding somatolactin (SL) was obtained by RT-PCR from pituitary glands of rock bream (Oplegnathus fasciatus). The full length cDNA of rock bream somatolactin (rbSL) is 1636 bp long. It contains a 696 bp open reading frame encoding a signal peptide of 24 amino acids (an) and a mature protein of 207 aa. rbSL has seven cysteine residues$(Cys^{5},\; Cys^{15},\; Cys^{42},\; Cys^{65},\; Cys^{181},\; Cys^{198}\; $and $Cys^{206})$ and two potential N-glycosylation sites at positions $Asn^{121}$and $Asn^{153}$. The rbSL shares 61.1∼92.6% amino acid sequence similarities and 63∼92.6% nucleotide sequence identities with other teleost SLs, except for goldfish and channel catfish SL. Amino acid sequence alignment revealed that rbSL has four conserved domains $(A_{SL},\; B_{SL},\; C_{SL}and\; D_{SL})$ common to all SLs. Out of these domains, $(A_{SL},\; B_{SL},\; C_{SL}and\; D_{SL})$, are also conserved in all teleost growth hormones and prolactins. The cDNA of rbSL has been cloned into pET expression vector in order to produce recombinant rbSL in E. coli BL2l(DE3) cells. The recombinant protein showed a molecular weight of 27 kDa in SDS-PAGE.