pGAPZα C

The glyceraldehyde-3-phosphate dehydrogenase （GAPDH） enzyme is constitutively

expressed at high levels in many organisms, including Pichia pastoris. The promoter of 

the gene （GAP） encoding the GAPDH protein has recently been characterized and shown 

to express recombinant proteins to high levels in Pichia pastoris, depending on the 

carbon source used （Waterham et al., 1997）. The level of expression seen with the GAP

promoter （PGAP） can be slightly higher than that obtained with the AOX1 promoter. 

The pGAPZ A, B, and C vectors （2.9 kb） and pGAPZα A, B, and C （3.1 kb） vectors use 

the GAP promoter to constitutively express recombinant proteins in Pichia pastoris. 

Proteins can be expressed as fusions to a C-terminal peptide containing the myc epitope 

for detection and a polyhistidine tag for purification on metal-chelating resin （i.e. 

ProBondô）. In addition, pGAPZα produces proteins fused to an N-terminal peptide 

encoding the Saccharomyces cerevisiae α-factor secretion signal. Both vectors are 

supplied in three reading frames to facilitate in frame cloning with the C-terminal tag 

and/or the N-terminal secretion signal. Selection of these vectors is based on the dominant 

selectable marker, Zeocinô, which is bifunctional in both Pichia and E. coli.