SUMMARY: Differential extraction of Cafrom the cytoplasmic and vacuolar pools of the yeast , using DEAE-dextran, revealed that most of the cellular Cawas bound, precipitated or sequestered within the vacuole. When the concentration of Cain the medium was raised from 10m to 10M. cytoplasmic Cahomeostasis was maintained at 5·8 × 10to 2·3 × 10M, whereas the vacuoles accumulated higher concentrations of Ca. The results indicate that the vacuoles function as a cytoplasmic Cabuffering system and as the major sequestering organelle for Ca. A respiratory-deficient mutant (ρ°) displayed a similar intracellular distribution of Cato the wild-type. When cells were permeabilized by DEAE-dextran the vacuoles were still capable of Cauptake. This uptake proceeded without the addition of ATP or glucose in fresh preparations but required the addition of ATP after incubation of the permeabilized cells in buffered sorbitol for 2 h. The results are consistent with the proposed CaHantiport in the vacuolar membrane, which is driven by Δμ formed by the H-ATPase pumping Hinto the vacuole.


Article metrics loading...

Loading full text...

Full text loading...


Most cited this month Most Cited RSS feed

This is a required field
Please enter a valid email address
Approval was a Success
Invalid data
An Error Occurred
Approval was partially successful, following selected items could not be processed due to error