Phototransformation of protochlorophyllide (Pchlide) to chlorophyllide (Chlide). chlorophyllide a + NADP(+) = H(+) + NADPH + protochlorophyllide a Porphyrin-containing compound metabolism; chlorophyll biosynthesis. Part of the FLU-containing chloroplast membrane complex composed of FLU, CRD1, PORB, PORC, CHLP and HEMA1. Prolamellar body of etiolated seedling. A number of isoforms are produced. According to EST sequences. Expressed in flowers, upper leaves, rosette and cauline leaves, stem. Not detectable in non-photosynthetic tissues such as roots and seeds. Up-regulated by light. Not under circadian regulation. No visible phenotype at the levels of the whole plant or chloroplast ultrastructure; due to the redundancy with PORB. Porb and porc double mutants have a seedling-lethal pale-yellow xantha phenotype at the cotyledon stage, contain only small amounts of Chla, and possess chloroplasts with mostly unstacked thylakoid membranes. Belongs to the short-chain dehydrogenases/reductases (SDR) family. POR subfamily.