The main sites for oxidative deamination are:

Only liver mitochondria contain glutamate dehydrogenase (GDH) which deaminates glutamate to alpha keto glutarate plus ammonia. The hydrolysis of glutamine also yields NH3 but this occurs mainly in the kidney where the NH4+ excretion is required for acid-base regulation. Reference: Vasudevan 7th  ed, pg 202