2-oxoglutarate + L-2,4-diaminobutanoate = L-aspartate 4-semialdehyde + L-glutamate Amine and polyamine biosynthesis; 1,3-diaminopropane biosynthesis; 1,3-diaminopropane from L-aspartate 4-semialdehyde: step 1/2. Belongs to the class-III pyridoxal-phosphate-dependent aminotransferase family.