Transfer of C3 units between the cytosol of mesophyll and bundle sheath cells to maintain a nitrogen-carbon balance in the C4-dicarboxylic pathway. 2-oxoglutarate + L-alanine = L-glutamate + pyruvate Photosynthesis; C4 acid pathway. Amino-acid degradation; L-alanine degradation via transaminase pathway; pyruvate from L-alanine: step 1/1. Homodimer. Mesophyll and bundle sheath cells. By light. The N-terminus is blocked. Belongs to the class-I pyridoxal-phosphate-dependent aminotransferase family. Alanine aminotransferase subfamily.