resistance genes for ampicillin u03b2 lactamases tetracycline and chloramphenicol chloramphenicol acetyltransferase examples of such markers typically used in mammalian expression vectors include the gene for adenosine deaminase ada aminoglycoside phosphotransferase neo g418 dihydrofolate reductase dhfr hygromycin b phosphotransferase hph thymidine kinase tk and xanthine guanine phosphoriboseyltransferase xgprt gpt in another preferred embodiment the expression system used is one driven by the baculovirus polyhedrin promoter the polynucleotide encoding cds can be manipulated by standard techniques in order to facilitate cloning into the baculovirus vector see ausubel et al supra a preferred baculovirus vector is the pbluebac vector invitrogen sorrento calif the vector carrying a polynucleotide encoding cds is transfected into spodoptera frugiperda sf9 cells by standard protocols and the cells are cultured and processed to produce the recombinant polypeptide see summers et al a manual for methods of baculovirus vectors and insect cell culture procedures texas agricultural experimental station the polynucleotides of the present invention can be expressed in any number of different recombinant dna expression systems to generate large amounts of polypeptide included within the present invention are cds polypeptides having native glycosylation sequences and deglycosylated or unglycosylated polypeptides prepared by the methods described below examples of expression systems known to the skilled practitioner in.