Proline Rich Transmembrane Protein 4 (PRRT4)

PRRT4, Belongs to the CD225 family. A transmembrane protein is a protein that spans the entire biological membrane. Transmembrane proteins aggregate and precipitate in water. They require detergents or nonpolar solvents for extraction, although some of them (beta-barrels) can be also extracted using denaturing agents.

Proline-rich proteins (PRPs) is a class of intrinsically unstructured proteins (IUP) containing several repeats of a short proline-rich sequence.Many tannin-consuming animals secrete a tannin-binding protein (mucin) in their saliva. Tannin-binding capacity of salivary mucin is directly related to its proline content. Example of this class of protein is IB5, a human parotid salivary protein known to bind with polyphenols (binding responsible for the astringency mouth feel).