P – Protein (Phloem Protein)
(Structure, Classification and Functions of Phloem Proteins)
What are P Proteins?
Ø P Proteins (Phloem Proteins) are a category of proteins found in the sap of the sieve tubes of the phloem of Angiospermic plants.
Ø P-proteins were also as called ‘slime bodies’ of ‘slime’ in the old literature.
Ø P proteins are usually found in the phloem of dicot plants.
Ø They are very rarely reported in monocots.
Ø P proteins are completely absent in the phloem of Pteridophytes and Gymnosperms.
Ø P proteins occur in different forms in the different developmental stages of sieve tubes.
Ø P proteins can exist in the sieve tubes as tubular, globular, fibrillar, granular and crystalline forms.
Ø P proteins are highly polar molecules and they can form gel like substance in the presence of water.