| 摘要 |
Yeast cell comprising a DNA construct that provides for the expression and secretion of a non-yeast protein is claimed, the DNA construct comprising a coding sequence under the control of yeast-recognised transcription initiation and termination sequences, the coding sequence encoding a precursor polypeptide comprising leader sequence and the non-yeast protein linked by a processing site that provides for the cleavage of the non-yeast protein from the precursor polypeptide, where the leader sequence is 25-50 N-terminal residues of the precursor polypeptide and comprises the signal peptide of a yeast a-factor precursor and a single glycosylation site. The non-yeast protein may be a mammalian protein eg insulin-like growth factor I or a precursor of human insulin eg human proinsulin or insulin a- and insulin b-chains linked by a yeast-recognised processing site cleaved in vivo, eg a processing site cleaved by the KEX2 gene prod of Saccharomyces. Also claimed is a double-stranded DNA molecule comprising a region encoding a precursor polypeptide secretable by a yeast host, the region, with reference to one of the strands, having the structure (I) 5'-AF-CH0-Xn-S-Gene-3' (I) (AF encodes a yeast a-factor signal; CH0 encodes a glycosylation site; Xn encodes a polypeptide of n amino acids in length that does not contain a glycosylation site or a processing site that provides for cleavage of the precursor polypeptide in vivo by yeast; n is 0-30; Gene encodes a non-yeast protein; S encodes a processing site that provides for cleavage of the precursor polypeptide, eg a dipeptide eg 5'-Lys-Arg-3' or 5'-Arg-Arg-3' recognised by the KEX2 endopeptidase).
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