Beauchamp J R, Woodman P G
Division of Biochemistry, School of Biological Sciences, University of Manchester Medical School, U.K.
Biochem J. 1994 Oct 15;303 ( Pt 2)(Pt 2):647-55. doi: 10.1042/bj3030647.
The effect of the protein phosphatase inhibitor okadaic acid on transferrin receptor internalization and recycling was examined in HeLa and K562 cells. Okadaic acid inhibited receptor uptake by more than 85% in both cell lines, whereas it affected transferrin recycling to differing degrees: recycling in HeLa cells was inhibited by greater than 90%, compared with only 65% in K562 cells. Okadaic acid also caused a marked redistribution of receptors in each cell line, which was accounted for by the difference in the extent to which transferrin uptake and recycling were inhibited. These effects were most likely mediated by a protein kinase, as they were delayed by 10-15 min and could be suppressed by prior incubation with certain protein kinase inhibitors. In addition, it was found that specific kinase inhibitors affected basal rates of transferrin uptake and recycling, although the extent of these effects differed between cell lines. Together, these results suggest that a complex pattern of protein phosphorylation influences the flux of the endocytic pathway in interphase cells.
在HeLa细胞和K562细胞中研究了蛋白磷酸酶抑制剂冈田酸对转铁蛋白受体内化和再循环的影响。在这两种细胞系中，冈田酸均抑制受体摄取超过85%，而其对转铁蛋白再循环的影响程度不同：HeLa细胞中的再循环被抑制超过90%，而K562细胞中仅为65%。冈田酸还导致每个细胞系中受体的明显重新分布，这是由转铁蛋白摄取和再循环受抑制程度的差异所致。这些效应很可能由蛋白激酶介导，因为它们延迟10 - 15分钟，并且可以通过预先与某些蛋白激酶抑制剂孵育来抑制。此外，发现特定的激酶抑制剂影响转铁蛋白摄取和再循环的基础速率，尽管这些效应的程度在不同细胞系之间有所不同。总之，这些结果表明，复杂的蛋白磷酸化模式影响间期细胞内吞途径的通量。
