Expansine

Expansinsins represent a large group of plant proteins with multiple functions.
They increase the permeability of the cell wall and thus enable plants to absorb nutrients from the soil.
They also enable plants to better process biotic and abiotic stress. In soybeans (Gylcin max), beta-expansins are enriched in the root nodules, which express legumes for nitrogen enrichment. There they regulate the growth process. Beta-expansins, together with cyn d 1, are a major allergen in patients with sensitization to Bermuda pollen(dogtooth grass).

Experimental data indicate that the beta-expansions could possibly be novel cysteine proteases. It is assumed that the proteolytic activity of Phl p 1, similar to that shown for Der p 1 (see below house dust mite), is important for the sensitization and manifestation of allergy.

1. Sampedro J et al (2015) Evolutionary divergence of β-expansin structure and function in grasses parallels emergence of distinctive primary cell wall traits. Plant J 81:108-120.
2. Zhou J et al (2013) Overexpression of β-expansin gene GmEXPB2 improves phosphorus efficiency in soybean. Physiol Plant 150:194-204.