Goldfine I D, Smith G J, Wong K Y, Jones A L
Proc Natl Acad Sci U S A. 1977 Apr;74(4):1368-72. doi: 10.1073/pnas.74.4.1368.
Human cultured lymphocytes (IM-9) were used to demonstrate that insulin can enter the intact cell and bind to the nucleus. When these lymphocytes were incubated with 125I-labeled insulin, specific cellular uptake reached a maximum within 2 min and remained at a plateau for 90 min or longer. Partially purified nuclei from such cells contained approximately 15-20% of the total cellular radioactivity. Nuclei freed of all other cellular fractions (by washing the partially purified nucleic with Triton X-100) bound approximately 7% of the total cellular radioactivity. In contrast to the rapid uptake of labeled insulin into the intact cell, specific binding to the nucleus was half-maximal after 5 min of incubation and maximal after 90 min. Both the cellular uptake and subsequent nuclear binding of labeled insulin were progressively inhibited by increasing concentrations of unlabeled hormone. Independent evidence for the nuclear binding of insulin was obtained by preparing autoradiographs of lymphocytes incubated for various times with labeled insulin. Such preparations strongly suggest that insulin binds to the plasma membrane, enters the cytosol, and then binds to the nucleus.
人类培养淋巴细胞（IM-9）被用于证明胰岛素能够进入完整细胞并与细胞核结合。当这些淋巴细胞与125I标记的胰岛素一起孵育时，特异性细胞摄取在2分钟内达到最大值，并在90分钟或更长时间内保持稳定。从这些细胞中部分纯化得到的细胞核含有约15%-20%的总细胞放射性。通过用Triton X-100洗涤部分纯化的细胞核，去除所有其他细胞成分后，细胞核结合了约7%的总细胞放射性。与标记胰岛素快速进入完整细胞不同，与细胞核的特异性结合在孵育5分钟后达到最大值的一半，90分钟后达到最大值。标记胰岛素的细胞摄取和随后的细胞核结合均随着未标记激素浓度的增加而逐渐受到抑制。通过制备与标记胰岛素孵育不同时间的淋巴细胞放射自显影片，获得了胰岛素与细胞核结合的独立证据。这些制备结果有力地表明，胰岛素与质膜结合，进入细胞质，然后与细胞核结合。
