What is aspartate aminotransferase? More than just used for liver disease testing please.?

An aspartate aminotransferase (AST) test measures the amount of this enzyme in the blood. AST is normally found in red blood cells, liver, heart, muscle tissue, pancreas, and kidneys. AST formerly was called serum glutamic oxaloacetic transaminase (SGOT).

Low levels of AST are normally found in the blood. When body tissue or an organ such as the heart or liver is diseased or damaged, additional AST is released into the bloodstream. The amount of AST in the blood is directly related to the extent of the tissue damage. After severe damage, AST levels rise in 6 to 10 hours and remain high for about 4 days.

The AST test may be done at the same time as a test for alanine aminotransferase, or ALT. The ratio of AST to ALT sometimes can help determine whether the liver or another organ has been damaged. Both ALT and AST levels can test for liver damage.

In animals, aspartate aminotransferase is involved in amino acid metabolism and production of an organic acid (oxaloacetate) that is part of the Krebs cycle and in plants in nitrogen and carbon metabolism.

Here is a more detailed explanation of the enzyme:
http://www.worthington-biochem.com/cgot/default.html

Here are a couple of descriptions of a pathway in which aspartate aminotransferase is involved, called the malate-aspartate shuttle which allows the electrons produced in glycosis and added to NADH to be brought across the mitochondrial inner membrane (which is impermeable to NADH) and thus allows the electrons from glycolysis to then enter the electron transport chain:

http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=mcb.figgrp.4359

http://www.mrc-dunn.cam.ac.uk/research/mitochondrial_carriers/malate-aspartate_shuttle.php