P-proteins (Phloem proteins) are components found in large amounts in phloem sieve tubes. The main function of these bodies is to seal off the sieve tube element or sieve cell by bringing about the blockage of sieve plate when the sieve element is injured. These bodies and callose together block the pores of sieve tube elements. P-protein bodies and callose form blocking plugs. These bodies remain along the walls of sieve tube elements. P-protein bodies are assigned some function in the translocation of food material in the sieve tubes but it is not universally accepted.