According to David H. Vroon and Zafar Israili aminotransferases (transaminases) are widely distributed among tissues, and are found in both cytoplasm and mitochondria, although this may vary between different aminotransferases:
Aminotransferases catalyze the redistribution of nitrogen between
amino acids and corresponding oxoacids participating in both protein
metabolism and gluconeogenesis. They are ubiquitous in their cellular
distribution.
Tissue activity for AST (aspartate aminotransferase) is as follows in decreasing concentration:
heart, liver, skeletal muscle, kidney, pancreas, spleen, lung, and
erythrocyte. Two distinct forms have been identified: a cytoplasmic,
or soluble isoenzyme, and a mitochondrial isoform...
The distribution and relative tissue concentration of ALT (alanine aminotransferase) is similar
but importantly different. Highest activity is found in the liver,
followed by kidney, myocardium, skeletal muscle, pancreas, spleen,
lung, and erythrocyte. ALT activity is found in the cytosol; organ- or
organelle-specific isoenzymes have not been demonstrated. The
concentration of ALT in hepatic cell cytoplasm is comparable to AST;
however, a mitochondrial ALT isoform is not found. In all other
tissues, ALT activity is significantly less than AST.
As regards deamination, there is a Wikipedia page for glutaminase, which indicates that it is found in the mitochondria of a variety of tissues. There are two isoforms, one especially active in the kidney, and the other in liver (although both are found in other tissues).
