TY - JOUR

T1 - Inhibition of endocytosis from coated pits by acidification of the cytosol

AU - Sandvig, Kirsten

AU - Olsnes, Sjur

AU - Petersen, Ole W.

AU - van Deurs, Bo

PY - 1988/1

Y1 - 1988/1

N2 - Binding and endocytosis of the ligands transferrin, epidermal growth factor (EGF), and ricin were measured in a number of different cell lines after treatment of cells with compounds that react with SH‐groups and under conditions where the cytosolic pH was lowered. N‐ethylmalemide and diamide irreversibly inhibited endocytosis of all ligands tested, whereas low pH in the cytosol strongly inhibited endocytosis of transferrin and EGF. Data obtained by electron microscopy indicated that the formation of coated vesicles from coated pits is inhibited in acidified cells. Entry of ricin was much less affected, and ricin endocytosed under these conditions was able to intoxicate the cells. At low pH in the cytosol there was a calcium‐dependent increase in the number of transferrin receptors at the cell surface. The increase was even larger in the presence of the calcium ionophore A23187, whereas it was completely blocked by the calmodulin antagonists trifluoperazine and W7. The results show that endocytosis from coated pits can be inhibited in a reversible way by acidification of the cytosol and they suggest that a second pathway of endocytosis exists, possibly involving formation of vesicles from uncoated areas of the membrane.

AB - Binding and endocytosis of the ligands transferrin, epidermal growth factor (EGF), and ricin were measured in a number of different cell lines after treatment of cells with compounds that react with SH‐groups and under conditions where the cytosolic pH was lowered. N‐ethylmalemide and diamide irreversibly inhibited endocytosis of all ligands tested, whereas low pH in the cytosol strongly inhibited endocytosis of transferrin and EGF. Data obtained by electron microscopy indicated that the formation of coated vesicles from coated pits is inhibited in acidified cells. Entry of ricin was much less affected, and ricin endocytosed under these conditions was able to intoxicate the cells. At low pH in the cytosol there was a calcium‐dependent increase in the number of transferrin receptors at the cell surface. The increase was even larger in the presence of the calcium ionophore A23187, whereas it was completely blocked by the calmodulin antagonists trifluoperazine and W7. The results show that endocytosis from coated pits can be inhibited in a reversible way by acidification of the cytosol and they suggest that a second pathway of endocytosis exists, possibly involving formation of vesicles from uncoated areas of the membrane.

KW - coated pits

KW - cytosol

KW - endocytosis

KW - epidermal growth factor

KW - transferrin

UR - http://www.scopus.com/inward/record.url?scp=0023837074&partnerID=8YFLogxK

U2 - 10.1002/jcb.240360108

DO - 10.1002/jcb.240360108

M3 - Journal article

C2 - 2893802

AN - SCOPUS:0023837074

VL - 36

SP - 73

EP - 81

JO - Journal of supramolecular structure and cellular biochemistry

JF - Journal of supramolecular structure and cellular biochemistry

SN - 0733-1959

IS - 1

ER -