上饶市第四届人民代表大会第二次会议 关于上饶

DNA complementary to calf stomach mRNA has been synthesised and inserted into the Pstl site of pAT153 by G-C tailing. Clones containing sequences coding for prochymesin were recognised by colony hybridisation with cDNA extended from a chemically synthesised oligodeoxynucleotide primer, the sequence of which was predicted from the published amino acid sequence of calf prochymesin ¹ . Two clones were identified which together contained a complete copy of prochymesin mRNA. The nucleotide sequence is in substantial agreement with the reported amino acid sequence of prochymosin ² and shows that this protein has a mol.wt. of 40431 and chyemsin a mol.wt. of 35612. The sequence also indicates that prochyn is synthesised as a precursor melecule, preprochymosin, having a 16 amino acid hydrophobic leader sequence analogous to that reported for other secreted proteins ³ .