Catalyzes the reduction of 1-pyrroline-5-carboxylate (PCA) to L-proline. Does not catalyze the reverse reaction. L-proline + NADP(+) = 1-pyrroline-5-carboxylate + 2 H(+) + NADPH L-proline + NAD(+) = 1-pyrroline-5-carboxylate + 2 H(+) + NADH Inhibited by p-chloromercuribenzoate. Amino-acid biosynthesis; L-proline biosynthesis; L-proline from L-glutamate 5-semialdehyde: step 1/1. Can use either NADPH or NADH, but the activity observed with NADPH is severalfold greater. Belongs to the pyrroline-5-carboxylate reductase family.