Abstract:

[Objective]In order to provide theoretical basis for studying biological function and application of alpaca prolactin (PRL), the alpaca PRL cDNA sequence were cloned and analyzed. [Method] According to the known cDNA sequences from mammals, alpaca PRL primers was designed and the full-length cDNA of PRL from alpaca pituitary was cloned by RT-PCR and RACE techniques. [Results and Conclusions] The size of full-length cDNA of PRL from alpaca pituitary was 959 bp and it contained an open reading frame (ORF) of 687 bp which encoded PRL precursor protein with 229AA. PRL precursor protein was a single-chain polypeptide composed of 30-AA signal peptide and 199-AA mature peptide. The spatial structure of alpaca PRL protein was similar to human GH. The result of the sequence alignment showed that the amino acids composition of alpaca PRL was similar to most mammals, but the methionine at 81-AA (51-AA for mature peptide) may lead to different spatial structure which may impact functions of alpaca PRL. A phylogenetic tree constructed basing on the amino acid sequences of alpaca PRL and other organisms showed that the relationships between alpaca PRL and camel PRL were closest and that the evolution speed of alpaca was very slow with no "episodic" evolution pattern as most mammals such as primates, rodents and ruminant.