PROSITE documentation PDOC00725

Gamma-thionins family signature

The following small plant proteins are evolutionary related:

• γ-thionins from wheat endosperm (γ-purothionins) and barley (γ- hordothionins) which are toxic to animal cells and inhibit protein synthesis in cell free systems [1].
• A flower-specific thionin (FST) from tobacco [2].
• Antifungal proteins (AFP) from the seeds of Brassicaceae species such as radish, mustard, turnip and Arabidopsis thaliana [3].
• Inhibitors of insect α-amylases from sorghum [4].
• Probable protease inhibitor P322 from potato.
• A germination-related protein from cowpea [5].
• Anther-specific protein SF18 from sunflower [6]. SF18 is a protein that contains a γ-thionin domain at its N-terminus and a proline-rich C- terminal domain.
• Soybean sulfur-rich protein SE60 [7].
• Vicia faba antibacterial peptides fabatin-1 and -2.

In their mature form, these proteins generally consist of about 45 to 50 amino-acid residues. As shown in the following schematic representation, these peptides contain eight conserved cysteines involved in disulfide bonds.

          +-------------------------------------------+
          |          +-------------------+            |
          |          |                   |            |
        xxCxxxxxxxxxxCxxxxxCxxxCxxxxxxxxxCxxxxxxCxCxxxC
        *******************|***|                | |
                           +---|----------------+ |
                               +------------------+

'C': conserved cysteine involved in a disulfide bond.
'*': position of the pattern.