1. 6 Some proteins function to defend the organisms 1.6.1 Immunoglobins in vertebrates 1.6.2 Fibrinogen and thrombin in blood-clotting 1.6.3 Snake venom. bacterial toxins. and toxic plant proteins (ricin). 1. 7 Some proteins help regulate cellular or physiological activity 1.7.1 Growth factors and transcription factors regulate cell growth and differentiation 1.7.2 Hormones(e.g, insulin, growth hormon) coordinate activities of different cells in multicellular organisms.1.6 Some proteins function to defend the organisms 1.6.1 Immunoglobins in vertebrates 1.6.2 Fibrinogen and thrombin in blood-clotting 1.6.3 Snake venom, bacterial toxins, and toxic plant proteins (ricin). 1.7 Some proteins help regulate cellular or physiological activity 1.7.1 Growth factors and transcription factors regulate cell growth and differentiation 1.7.2 Hormones (e.g., insulin, growth hormon) coordinate activities of different cells in multicellular organisms