L-homoserine + NADP(+) = H(+) + L-aspartate 4-semialdehyde + NADPH L-homoserine + NAD(+) = H(+) + L-aspartate 4-semialdehyde + NADH Amino-acid biosynthesis; L-methionine biosynthesis via de novo pathway; L-homoserine from L-aspartate: step 3/3. Amino-acid biosynthesis; L-threonine biosynthesis; L-threonine from L-aspartate: step 3/5. Homodimer. Present with 48900 molecules/cell in log phase SD medium. Belongs to the homoserine dehydrogenase family.