Terminal methionyl bovine growth hormone and its use

DETAILED DESCRIPTION According to the present invention, synthetic DNA is provided for a substantial portion of the initial coding sequence of a heterologous gene insert, and optionally, upstream therefrom through the ATG translational start codon and ribosome binding site.
The critical portion of DNA is chemically synthesized, keeping in mind two factors: (1) the creation of a sequence that codes for the initial (N-terminus) amino acid sequence of a polypeptide comprising a functional protein or bioactive portion thereof and (2) the assurance that said sequence provides, on transcription, messenger RNA that has a secondary/tertiary conformational structure which is insufficient to interfere with its accessibility for efficient ribosomal translation, as herein defined.
Such chemical synthesis includes standard organic synthesis using modified mononucleotides as building blocks such as according to the method of Crea et al.
, Nucleic Acids Research 8, 2331 (1980) as well as the use of site directed mutagenesis of DNA fragments such as according to the method of Razin et al.
, Proc.
Natl.
Acad Sci (USA) 75, 4268 (1978) and the use of synthetic primers on certain appropriately sequenced DNA fragments followed by specific cleavage of the desired region.
The present invention is directed to a process of preparing DNA sequences comprising nucleotides arranged sequentially so as to encode the proper amino acid sequence of a given polypeptide.
This method involves the obtainment of a substantial portion of the DNA coding sequence of a given polypeptide via means other than chemical synthesis, most often by reverse transcription from requisite tissue and/or culture cell messenger RNA.
This fragment encodes the C-terminal portion of the polypeptide and is ligated, in accordance herewith, to a remainder of the coding sequence, obtained by chemical synthesis, optionally including properly positioned translational start and stop signals and upstream DNA through the ribosome binding site and the first nucleotide (+1) of the resultant messenger RNA