Conserved Site

Cereal seed allergen/trypsin and alpha-amylase inhibitor, conserved site (IPR006105)

Short name: Allergen/tryp_amyl_inhib_CS

Description

The seeds of cereals contain numerous serine protease and alpha-amylase inhibitors. These inhibitors can be grouped into families based on structural similarities. This domain identifies sequences belonging to the cereal (monocotyledon) trypsin/alpha-amylase inhibitor family [PMID: 2102817]. It includes those annotated solely as seed allergens or alpha-amyalse inhibitors [PMID: 7678765]. Many belong to MEROPS inhibitor family I6, clan IJ. Some are known to be inhibit trypsin (an S1 peptidase, IPR001254) [PMID: 14705960]. For some there is no direct evidence to suggest they any can inhibit trypsin or any other serine peptidase. Studies on the alpha-amylase inhibitor from Secale cereale (Rye) has demonstrated no activity against trypsin, and illustrates the necessity of exercising caution in assigning function based on sequence comparisons [PMID: 11137459].

The cereal trypsin/alpha-amylase inhibitor family consists of proteins of about 120 amino acids which contain 10 cysteine residues, all of which are involved in disulphide bonds [PMID: 2102817]. 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.
PROSITE patterns