Which vitamin, found in many orange and green vegetables, the immune system, builds body tissues, and in mucous production?

The answer is Vitamin C otherwise known as Ascorbic acid. It is naturally present in some foods, added to others and available in dietary supplement. Fruits and vegetables are the best sources of vitam C. Citrus fruits, tomatoes and tomato juice and potatoes are major contributors of vitamin C. 

Pro insulin undergoes extensive posttranslational modification along the production pathway .