Plant lipid transfer proteins

Plant lipid transfer protein / bifunctional inhibitor / seed storage protein, 4-helical domain
Oryza sativa Lipid Transfer Protein 1 bound to palmitic acid (black). Positive charge in blue; negative charge in red (PDB: 1UVB​).
Identifiers
Symbol	LTP/seed_store/tryp_amyl_inhib
Pfam	PF00234
Pfam clan	CL0482
InterPro	IPR016140
SMART	SM00499
CATH	1UVB
SCOP2	1UVB / SCOPe / SUPFAM
CDD	cd00010
Available protein structures: Pfam   structures / ECOD   PDB RCSB PDB; PDBe; PDBj PDBsum structure summary PDB PDB: 1UVB​ PDB: 1afh​ PDB: 1b1u​ PDB: 1be2​ PDB: 1bea​ PDB: 1bfa​ PDB: 1bip​ PDB: 1bwo​ PDB: 1cz2​ PDB: 1fk0​ PDB: 1fk1​
Also Pfam PF13016, PF14368; see the Pfam clan relationships.

Plant lipid transfer proteins, also known as plant LTPs or PLTPs, are a group of highly-conserved proteins of about 7-9kDa found in higher plant tissues.^[1][2] As its name implies, lipid transfer proteins facilitate the shuttling of phospholipids and other fatty acid groups between cell membranes.^[3] LTPs are divided into two structurally related subfamilies according to their molecular masses: LTP1s (9 kDa) and LTP2s (7 kDa).^[4] Various LTPs bind a wide range of ligands, including fatty acids with a C₁₀–C₁₈ chain length, acyl derivatives of coenzyme A, phospho- and galactolipids, prostaglandin B₂, sterols, molecules of organic solvents, and some drugs.^[2]

The LTP domain is also found in seed storage proteins (including 2S albumin, gliadin, and glutelin) and bifunctional trypsin/alpha-amylase inhibitors.^[5][6][7][8] These proteins share the same superhelical, disulfide-stabilised four-helix bundle containing an internal cavity.

There is no sequence similarity between animal and plant LTPs. In animals, cholesteryl ester transfer protein, also called plasma lipid transfer protein, is a plasma protein that facilitates the transport of cholesteryl esters and triglycerides between the lipoproteins.