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Cry proteins are crytalline proteins that are toxic and insecticidal in nature.

They are produced by bacteria called  Bacillus thuringiensis. The toxic protein is present in active form in bacteria which when ingested by an  insect leads to the activation of protein and subsequent death of insect.

Man has benefited from this protein by incorporating the Bt-toxin gene that produces the Cry protein in several crop plants like cotton. The incorporation of gene in plants makes them insect resistant and thus help in good yield and productivity.