GLP PROTEINS

What are GLP?

Molecular investigations during wheat germination have revealed unique developmentally regulated proteins, designated as germins, which show remarkable resistance to broad specificity proteases and to dissociation in SDS. Germins in cereals have an oxalate oxidase activity, which generates H2O2 from the oxidative breakdown of oxalate thereby playing a significant role in plant development and defense. Germins and germin like proteins (GLPs) are a class of developmentally regulated glycoproteins characterized by a beta-barrel core structure, a signal peptide, and are associated with the cell wall. GLPs exhibit a broad range of diversity in their occurrence and activity in organisms ranging from myxomycetes, bryophytes, pteridophytes, gymnosperms and angiosperms. Germins and GLPs are thought to play a significant role during zygotic and somatic embryogenesis (wheat and Pinus, respectively), salt stress (barley and Mesembryanthemum crystallinum), pathogen elicitation (wheat and barley), and heavy metal stress, etc. Characterization and cloning of some of the genes encoding germins and GLPs has facilitated a better understanding of their regulation and raised their potential of biotechnological application

Germin-like-proteins are present and have a number of various functions in many plant species. GLP are involved in the germination process and cell wall restructuring, take part in the osmotic regulation and play an active role in many defense responses to pathogens. As an example GLP5 will be described below.

GLP5

Gene: AT5G20630

Full name: Arabidopsis thaliana Germin 5

Function: encodes a plasodesmata-located protein involved in regulating primary root growth by controlling phloem-mediated allocation of resources between the primary and lateral root meristems

DNA and Protein Sequences

DNA Sequence:

Red color highlights the regulatory sequences (promoter and terminator) and yellow color shows the exone

Protein Sequence:

Secondary structures

The aminoacid sequence of GLP5 contains 5 alfa helixes and 10 beta sheets:

Intracellular expression

The highest intracellular expression of GLP5 was observed in the cell wall(44), which is tied with the function of germins. During cellular growth, the pH of th extracellular matrix is lowering, while the turgor pressure is increasing