BIO 211 Lecture Notes - Lecture 15: Glut1, Alanine, Leucine
4 Aug 2020
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Document Summary
Carrier-mediated transport enables molecules with low lipid solubility to traverse the blood-brain barrier. Glucose (primary energy substrate of brain) from blood enters brain by a transport protein. Glucose transport protein(glut-1) is highly enriched in brain capillary endothelial cells. The brain does not require insulin for glucose to enter. But a glut-1 deficiency(genetic mutation) can have severe learning difficulties- low glucose sugar levels in. Csf but not in blood will identify the condition. Essential amino acids cannot be synthesized by the brain so they must be supplied from protein breakdown and diet. Phenylalanine, leucine, tyrosine, isoleucine, valine, teyptophan, methionine, and histidine, and also the precursor of dopamine, l- Dopa, enter the brain as rapidly as glucose. Transported into the brain by leucine-perferring or the l-type transport proteins. They compete with each other for entry into the brain- the elevation of plasma level of one will inhibit uptake of the others.
