RESUMO
"CapFinder" technology,which can be used to clone the full length of 5′ UTR sequence of mRNA,was described.This technology used the terminal transferase activity of certain MMLV RT variants that added 3-5 residues(predominantly dC) to the 3′end of the first-strand cDNA exhibited when MMLV RT reached the 5′cap structure of mRNA.In the reverse reaction system containing GGG oligo,the terminal transferase activity was harnessed by the GGG oligo whose terminal stretch of dG residues can anneal to the dC-rich cDNA tail and serve as an extended template for RT.After RT switch templates from the mRNA template to the GGG oligo,a complete cDNA copy of the original RNA was synthesized with the additional GGG oligo sequences at the end.5′UTR of mRNA can be amplified with GGG oligo as forward primer and a gene-specific reverse primer.5′UTR of Bt toxin receptor E-Cadherin gene in midgut of cotton bollworm was cloned.