Family

Cereal seed allergen/grain softness/trypsin and alpha-amylase inhibitor (IPR006106)

Short name: Allergen/soft/tryp_amyl_inhib

Overlapping homologous superfamilies

Family relationships

Description

The seeds of cereals contain numerous serine protease and alpha-amylase inhibitors. These inhibitors can be grouped into families based on structural similarities and many are described as seed allergens. This family of cereal (monocotyledon) allergens, trypsin/alpha-amylase inhibitors [PMID: 2102817] belong to MEROPS inhibitor family I6, clan IJ. Some are known to be serine protease inhibitors, active against S1 peptidases (IPR001254) [PMID: 14705960]. For some there is no direct evidence to suggest they any can inhibit serine peptidases and studies on the alpha-amylase inhibitor from Secale cereale (Rye) demonstrates no activity against trypsin, and illustrates the necessity of exercising caution in assigning function based on sequence comparisons [PMID: 11137459].

They consists of proteins of about 120 amino acids which contain 10 cysteine residues, all of which are involved in disulphide bonds. Some of these inhibitors are specific to trypsin, others to alpha-amylase, and a few are bifunctional. The schematic representation of the structure of these inhibitors is shown below:

                       +----------------------------+
           +----------+|   +-+                      |
           |          ||   | |                      |
  xxCxxxxxxCxxxCxxxxxxCCxxxCxCxxxxxxxxxxxxxCxxxxxxxxCxxxxxxxCxxxx
    |          |                           |                |
    |          +---------------------------+                |
    +-------------------------------------------------------+

'C': conserved cysteine involved in a disulphide bond.

The 3D structure of the bifunctional alpha-amylase/trypsin inhibitor (RBI) from seeds of Eleusine coracana (Indian finger millet) has been determined in solution using multidimensional 1H and 15N NMR spectroscopy [PMID: 7599120]. The inhibitor forms a globular 4-helix motif with a simple 'up-and-down' topology, and includes a short anti-parallel beta-sheet [PMID: 7599120].

GO terms

Biological Process

No terms assigned in this category.

Molecular Function

GO:0004867 serine-type endopeptidase inhibitor activity

Cellular Component

No terms assigned in this category.

Contributing signatures

Signatures from InterPro member databases are used to construct an entry.
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PANTHER