I am expressing a Mab in mammalian cells. Is it necessary to incorporate a Kozak sequence before the ATG initiation codon to assure that the expression happens? And also do I need to add an extra RBS and TATA box between the heavy chain and light chain since I am cloning heavy and light in a stretch under single cmv promoter. I will be using pcDNA3.1 vector. If any of this is to be used, do you have any sequence suggestion?