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Molecular Biology Problem Solver 52

Molecular Biology Problem Solver 52. Sách được nhiều nhà khoa học có uy tín, nhiều kinh nghiệm trong nghiên cứu thực nghiệm trình bày những vấn đề thường hay phát sinh trong phòng thí nghiệm. Do vậy mà sách không trình bày các protocol hay quy trình như các sách khác, thay vào đó các tác giả sẽ trình bày các vấn đề nhằm giúp giúp đọc giả: Tự nâng cao khả năng chẩn đoán nguyên nhân khi gặp các vấn để về kỹ thuật, quy trình, hóa chất, thuốc thử trong quá trình thực nghiệm trong phòng thí. | Table 16.2 Promoter Strength Table Promoter Source Strength Reference EF-1a Human elongation factor 1a 40-160 Mizushima and Nagata 1990 CMV Human cytomegalovirus immediate-early gene 4 Boshart et al. 1985 RSV Rous sarcoma virus LTR 2 Gorman et al. 1982 SV40 late Simian virus 40 Late gene 1.1 Wenger Moreau and Nielsen 1994 SV40 early Simian virus 40 Early gene 1 Adeno major Adenovirus major 0.4 Mansour Grodzicker and late late promoter Tjian 1986 Beta-globin Mouse beta-globin promoter 0.2 Hamer Kaehler and Leder 1980 Beta-actin Human beta-actin promoter ND Ng et al. 1985 Note SV40 early promoter strength set as 1 for comparative purposes and the numbers indicate how much stronger these promoters are. Promoters Promoters are DNA sequences that recruit cellular factors and RNA polymerase to activate transcription of a particular gene. They must contain a transcriptional start site a CAAT box and TATA box. Examples of various mammalian promoters are given in Table 16.2. The promoter strength is based on a compilation of comparative experiments where various promoters were compared in transient experiments using the R1610 cell line Thirion Banville and Noel 1976 . The strength of EF-1a and CMV was derived from a comparison to the RSV LTR involving stable expression of various monoclonal antibodies and tPA Trill 1998 unpublished . The EF-1a promoter available from Invitrogen is by far the strongest promoter and a good choice if you want quick high-level expression. Polyadenylation Regions Polyadenylation occurs at a consensus sequence AAUAAA and results in increased mRNA stability. Cleavage after the U by poly A polymerase adds a string of adenylate residues Wahle and Keller 1992 . As with the promoters there are a number of sources of polyadenylation regions. Several examples are shown in Table 16.3. Eukaryotic Expression 507 Table 16.3 Polyadenylation Regions Poly A Region Source Efficiency BGH Bovine growth hormone 3 SV40 late Simian virus 40 2 TK Herpes simplex virus