In the body we almost always assume that glutamate exists as glutamate rather than glutamic acid. It is so commonly glutamate yet glutamic acid and glutamate share the abbreviations of Glu and E. From the wikipedia page:
The side chain carboxylic acid functional group has a pKa of 4.1 and therefore exists almost entirely in its negatively charged deprotonated carboxylate form at pH values greater than 4.1; therefore, it is negatively charged at physiological pH ranging from 7.35 to 7.45.
Given that the pKa of glutamate is 4.1, is their any biological situation (a cell type, organel etc.) that glutamic acid is preferred?
Additionally, does this have any large biochemical implications, or is that outweighed by the (relatively speaking) "extreme" acidic environment?