TY - JOUR

T1 - Acidification of the cytosol inhibits endocytosis from coated pits

AU - Sandvig, K.

AU - Olsnes, S.

AU - Petersen, O. W.

AU - Van Deurs, B.

PY - 1987

Y1 - 1987

N2 - Acidification of the cytosol of a number of different cell lines strongly reduced the endocytic uptake of transferrin and epidermal growth factor. The number of transferrin binding sites at the cell surface was increased in acidified cells. Electron microscopic studies showed that the number of coated pits at the cell surface was not reduced in cells with acidified cytosol. Experiments with transferrin-horseradish peroxidase conjugates and a monoclonal anti-transferrin receptor antibody demonstrated that transferrin receptors were present in ~75% of the coated pits both in control cells and in cells with acidified cytosol. The data therefore indicate that the reason for the reduced endocytic uptake of transferrin at internal pH <6.5 is an inhibition of the pinching off of coated vesicles. In contrast, acidification of the cytosol had only little effect on the uptake of ricin and the fluid phase marker lucifer yellow. Ricin endocytosed by cells with acidified cytosol exhibited full toxic effect on the cells. Although the pathway of this uptake in acidified cells remains uncertain, some coated pits may still be involved. However, the data are also consistent with the possibility that an alternative endocytic pathway involving smooth (uncoated) pits exists.

AB - Acidification of the cytosol of a number of different cell lines strongly reduced the endocytic uptake of transferrin and epidermal growth factor. The number of transferrin binding sites at the cell surface was increased in acidified cells. Electron microscopic studies showed that the number of coated pits at the cell surface was not reduced in cells with acidified cytosol. Experiments with transferrin-horseradish peroxidase conjugates and a monoclonal anti-transferrin receptor antibody demonstrated that transferrin receptors were present in ~75% of the coated pits both in control cells and in cells with acidified cytosol. The data therefore indicate that the reason for the reduced endocytic uptake of transferrin at internal pH <6.5 is an inhibition of the pinching off of coated vesicles. In contrast, acidification of the cytosol had only little effect on the uptake of ricin and the fluid phase marker lucifer yellow. Ricin endocytosed by cells with acidified cytosol exhibited full toxic effect on the cells. Although the pathway of this uptake in acidified cells remains uncertain, some coated pits may still be involved. However, the data are also consistent with the possibility that an alternative endocytic pathway involving smooth (uncoated) pits exists.

UR - http://www.scopus.com/inward/record.url?scp=0023582912&partnerID=8YFLogxK

U2 - 10.1083/jcb.105.2.679

DO - 10.1083/jcb.105.2.679

M3 - Journal article

C2 - 2887575

AN - SCOPUS:0023582912

VL - 105

SP - 679

EP - 689

JO - Journal of Cell Biology

JF - Journal of Cell Biology

SN - 0021-9525

IS - 2

ER -