pSecTag2 A, B, and C vectors are fusion vectors requiring that you clone your gene of interest in frame with the initiation ATG of the N-terminal Igκ-chain leader sequence and/or the C-terminal myc epitope/polyhistidine tag. Three versions of this vector are provided to facilitate cloning. For proper expression,first determine which restriction sites are appropriate for ligation and then which vector will preserve the reading frame at BOTH the 5′ and the 3′ ends. It may be nece ssary to PCR your gene product to create a fragment with the appropriate restriction sites to clone in frame at both ends. Carefully inspect your gene and the multiple cloning site of each vector before cloning your gene of interest