Lanford R E, White R G, Dunham R G, Kanda P
Department of Virology and Immunology, Southwest Foundation for Biomedical Research, San Antonio, Texas 78284.
Mol Cell Biol. 1988 Jul;8(7):2722-9. doi: 10.1128/mcb.8.7.2722-2729.1988.
A previous study demonstrated the ability of a synthetic peptide homologous to the simian virus 40 T-antigen nuclear transport signal to induce the nuclear transport of carrier proteins and the dependence of peptide-induced transport on a positive charge at the lysine corresponding to amino acid 128 of T antigen. In this investigation synthetic peptides were utilized to examine the effect on transport of amino acid substitutions within the T-antigen nuclear transport signal. Nuclear transport was evaluated by immunofluorescence after microinjection of protein-peptide conjugates into the cytoplasm of mammalian cells. Substitution of other basic amino acids at position 128 revealed a hierarchy for nuclear transport. The rate of nuclear transport was most rapid when a lysine was at position 128 followed in descending order by arginine, D-lysine, ornithine, and p-aminophenylalanine. Peptide-induced nuclear transport was dependent upon a positively charged amino acid at positions 128 and 129, since substitutions of neutral asparagines at these positions abolished transport. However, partial transport was observed with the peptide having an asparagine at position 128 when a high number of peptides were conjugated to the carrier protein.
先前的一项研究表明，一种与猿猴病毒40 T抗原核转运信号同源的合成肽能够诱导载体蛋白的核转运，且肽诱导的转运依赖于与T抗原第128位氨基酸相对应的赖氨酸上的正电荷。在本研究中，利用合成肽来检测T抗原核转运信号内氨基酸替换对转运的影响。将蛋白质 - 肽偶联物显微注射到哺乳动物细胞的细胞质中后，通过免疫荧光评估核转运。在第128位替换其他碱性氨基酸揭示了核转运的一个等级体系。当第128位为赖氨酸时，核转运速率最快，其次依次为精氨酸、D - 赖氨酸、鸟氨酸和对氨基苯丙氨酸。肽诱导的核转运依赖于第128位和第129位带正电荷的氨基酸，因为在这些位置替换为中性的天冬酰胺会消除转运。然而，当大量肽与载体蛋白偶联时，在第128位为天冬酰胺的肽中观察到了部分转运。
