All are involved in non toxic transport of ammonia except:
Transport of Ammonia 
Free ammonia is toxic to cells especially to brain. Excess ammonia generated has to be converted to nontoxic form then transported to liver to enter into urea cycle.

Transport of Ammonia from most of the tissues including the brain
Transport of Ammonia from skeletal muscle

Transport of Ammonia from most of the tissues including the brain.

As Glutamine with the help of the enzyme Glutamine Synthetase.

Glutamine Synthetase

Ammonia formed in most tissues including the brain is trapped by Glutamate to form Glutamine
This is called first line trapping of ammonia
ATP is required for this reaction.

Glutaminase

In the liver, glutaminase removes the ammonia from Glutamine.
Ammonia enter into urea cycle in the liver.

Transport of Ammonia from skeletal muscle.

From Skeletal Muscle as Alanine
In skeletal muscle, excess amino groups are generally transferred to pyruvate to form alanine.

Key Concept:
Glutamine synthase converts NH3 to nontoxic glutamine. Glutaminase releases NH3 for use in urea synthesis.
Glutamine synthetase
Glutaminase
Alanine cycle
SGPT