HIGH‐AFFINITY TRANSPORT AND PHOSPHORYLATION OF 2‐DEOXY‐d‐GLUCOSE IN SYNAPTOSOMES1,2

I Diamond, RA Fishman - Journal of Neurochemistry, 1973 - Wiley Online Library
I Diamond, RA Fishman
Journal of Neurochemistry, 1973Wiley Online Library
Deoxy‐d‐glucose (2 DG) entered synaptosomes (from rat brain) by a high‐affinity, Na+‐
independent glucose transport system with a Km, of 0.24 mM. 3‐O‐methyl‐glucose, D‐
glucose, and phloretin were competitive inhibitors of 2‐DG transport with Ki's of 7 mM, 64
μM, and 0· 75 μM, respectively. Insulin was without effect. 2‐DG uptake was also saturable
at high substrate concentrations with an apparent low affinity Km, of 75 mM, where the Kl, for
glucose was 17.5 mM. We are not certain whether the rate‐limiting step for the low‐affinity …
Abstract
2‐Deoxy‐d‐glucose (2 DG) entered synaptosomes (from rat brain) by a high‐affinity, Na+‐independent glucose transport system with a Km, of 0.24 mM. 3‐O‐methyl‐glucose, D‐glucose, and phloretin were competitive inhibitors of 2‐DG transport with Ki's of 7 mM, 64 μM, and 0·75 μM, respectively. Insulin was without effect. 2‐DG uptake was also saturable at high substrate concentrations with an apparent low affinity Km, of 75 mM, where the Kl, for glucose was 17.5 mM. We are not certain whether the rate‐limiting step for the low‐affinity uptake system is attributable to transport or phosphorylation. However, the high‐affinity glucose transport system probably is a special property of neuronal cell membranes and could be useful in helping to distinguish separated neurons from glial cells.
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