1 Diagram (simplified) of the reactions of photorespiration, involving chloroplast, peroxisome and mitochondrion. The process begins with the wasteful oxidative reaction of rubisco in the chloroplast stroma, producing glycolate, which enters peroxisomes by a special porin protein channel in their membrane. Its conversion to glyoxylate releases hydrogen peroxide (broken down by catalase). Transamination to glycine, subsequent conversions in mitochondria, and return to peroxisomes and thence to chloroplasts allows some of the original carbon to conserved by its re-entry into the photosynthetic carbon reduction cycle.

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