Storage Protein Synthesis


Seed storage proteins are synthesised in the endoplasmic reticulum and accumulate in protein bodies in the cotyledon and endosperm storage tissues during seed development. Their synthesis relies on remobilisation of nitrogen from vegetative tissues. They are adapted for storing rapidly and in an inert form a high concentration of remobilisable nitrogen. Upon germination, they provide the seedling with amino acids during the heterotrophic growth phase. They also represent a major protein source for humans and livestock. Although having limiting quantities of essential amino acids, notably lysine and methionine, a combination of cereal and legume seed proteins, for example constitutes a good dietary amino acid balance for monogastric animals. Seed proteins have been classified by their differing solubilities. With the benefit of sequence data, we now know that within a solubility class different sequence types may exist. Interestingly, despite their contrasted primary sequences, the conservation of short sequence motifs shows that different storage protein classes are derived from a common evolutionary ancestor. Storage proteins embrace a large range of valuable technological properties, which find varied uses in the food industry.

Key Concepts

  • Seed storage proteins have evolved to store nitrogen efficiently as a source for the germinating seedling.
  • Most monocotyledons store mainly prolamin storage proteins, whereas dicotyledons store mainly globulins.
  • Prolamins consist mainly of short tandem repeats of noncharged amino acids, which renders them insoluble in water.
  • Globulins are assembled into multimers that reduce their solubility.
  • Seeds contain antinutritional compounds that reduce digestibility of the storage proteins by humans or livestock unless eliminated by breeding or processing.
  • The secondary/tertiary structure of cereal glutelins confers the property of viscoelasticity, of fundamental importance to breadmaking.
  • Storage proteins are encoded by multigene families, and mutations having a major effect on their accumulation are mostly in trans, at loci regulating their synthesis or deposition in protein bodies.
  • The seed's structure and its development are highly adapted to permit a rapid accumulation of storage products during the limited period of seed maturation.
  • Storage protein deposition relies on remobilisation of nitrogen from vegetative tissue.
  • Storage protein remobilisation during germination involves activation of preexisting proteases and induction of de novo synthesis.

Keywords: endosperm; cotyledon; prolamin; glutelin; globulin; vacuole; protein body; remobilisation; embryo; heterotrophic

Figure 1. Thin section of immature (20 days after fertilisation) seed of barrel medick (Medicago truncatula). Immunofluorescence labelling of embryo cells with antivicilin antibodies which localises this storage protein in the protein storage vacuoles (green). The remaining cellular structures are visualised with propidium iodide fluorescence (red). Micrograph kindly provided by M. Abirachid‐Darmency and S. Ochatt (INRA Agroécologie, Dijon, France)
Figure 2. Storage protein structures. (a) Schematic view of a globulin hexamer (glycinin from soya bean), based on X‐ray crystallography studies. The six subunits are indicated in different colours (Adachi, M., et al. (2003). Crystal structure of soybean 11S globulin: Glycinin A3B4 homohexamer. Proceedings of the National Academy of Sciences 100 (12): 7395–7400.) (b) Predicted HMW glutenin structures. The polypeptide backbone consists of a central rod‐like beta‐spiral (blue) with alpha‐helical globular N‐ and C‐terminal regions containing cysteine residues. The rods may associate to form HCP (‘hexagonal closed polymers’, Kuktaite et al., ). They are also thought to form longer chains by cystine cross‐bridge formation involving subterminal residues.
Figure 3. Protein body formation in rice endosperm cells. Prolamin mRNA (blue) and glutelin mRNA (green) locate to different ER domains, the prolamin mRNA to the sites of formation of type‐I protein bodies (PB‐1) and glutelin mRNA to the cisternal ER (C‐ER). Prolamins coalesce in situ to form type‐I protein bodies, whereas glutelins are transported via the Golgi apparatus to the protein storage vacuoles, where type‐II protein bodies form. Figure reproduced with permission from: Crofts et al., Biochem. Cell Biol. 83: 728–737 (2005).
Figure 4. Interactions between the LAFL ‘master regulators’ of storage protein synthesis in Arabidopsis thaliana. LEC1 controls the synthesis of ABI3, FUS3 and LEC2. LEC1, ABI3, LEC2 and FUS3 all act positively on transcription of seed storage protein genes. ABI3 and FUS3 autoregulate their own synthesis and are activated by LEC2. Adapted from Fatihi et al. .


Adachi M, Kanamori J, Masuda T, et al. (2003) Crystal structure of soybean 11S globulin: glycinin A3B4 homohexamer. Proceedings of the National Academy of Sciences 100 (12): 7395–7400.

Angelovici R, Fait A, Fernie AR and Galili G (2011) A seed high‐lysine trait is negatively associated with the TCA cycle and slows down Arabidopsis seed germination. The New Phytologist 189: 148–159.

Berger F (2007) Endosperm development. In: eLS. Chichester: John Wiley & Sons, Ltd. DOI: 10.1002/9780470015902.a0020098.

Bewley J and Black M (1985) Seeds: germination, structure and composition. In: Seeds: Physiology of Development and Germination, pp. 1–33, chap. 1. New York: Plenum Press. ISBN 978-0-306-44748-8.

Cheng WH, Taliercio EW and Chourey PS (1996) The Miniature1 seed locus of maize encodes a cell wall invertase required for normal development of endosperm and maternal cells in the pedicel. Plant Cell 8 (6): 971–983.

Clemente A, Arques MC, Dalmais M, et al. (2015) Eliminating anti‐nutritional plant food proteins: the case of seed protease inhibitors in pea. Plos One 10 (8): e0134634.

Demidov D, Horstmann C, Meixner M, et al. (2003) Additive effects of the feed‐back insensitive bacterial aspartate kinase and the Brazil nut 2S albumin on the methionine content of transgenic narbon bean (Vicia narbonensis L.). Molecular Breeding 11: 187–201.

Dunwell JM (1998) Cupins: a new superfamily of functionally diverse proteins that include germins and plant storage proteins. Biotechnology and Genetic Engineering Reviews 15 (1): 1–32.

Fatihi A, Boulard C, Bouyer D, et al. (2016) Deciphering and modifying LAFL transcriptional regulatory network in seed for improving yield and quality of storage compounds. Plant Science 250: 198–204.

Frizzi A, Caldo RA, Morrell JA, et al. (2010) Compositional and transcriptional analyses of reduced zein kernels derived from the opaque2 mutation and RNAi suppression. Plant Molecular Biology 73: 569–585.

Fukuda M, Kawagoe Y, Murakami T, et al. (2016) The dual roles of the golgi transport 1 (GOT1B): RNA localization to the cortical endoplasmic reticulum and the export of proglutelin and α‐globulin from the cortical‐ER to the golgi. Plant and Cell Physiology 57 (11): 2380–2391.

Galili G and Amir R (2013) Fortifying plants with the essential amino acids lysine and methionine to improve nutritional quality. Plant Biotechnology Journal 11 (2): 211–222.

Gillikin JW, Zhang F, Coleman CE, et al. (1997) A defective signal peptide tethers the floury‐2 zein to the endoplasmic reticulum membrane. Plant Physiology 114: 345–352.

Golan A, Matitiyho I, Avraham T, et al. (2005) Soluble methionine enhances accumulation of a 15 kDa zein, a methionine‐rich storage protein, in transgenic alfalfa but not in transgenic tobacco plants. Journal of Experimental Botany 56: 2443–2452.

Guo X, Yuan L, Chen H, et al. (2013) Nonredundant function of zeins and their correct stoichiometric ratio drive protein body formation in maize endosperm. Plant Physiology 162 (3): 1359–1369.

Harada J, Belmonte MF and Kwong RW (2010) Plant embryogenesis (zygotic and somatic). In: eLS. Chichester: John Wiley & Sons, Ltd. DOI: 10.1002/9780470015902.a0002042.pub2.

Holding DR (2014) Recent advances in the study of prolamin storage protein organization and function. Frontiers in Plant Science 5: 276.

Huang S, Kruger DE, Frizzi A, et al. (2005) High‐lysine corn produced by the combination of enhanced lysine biosynthesis and reduced zein accumulation. Plant Biotechnology Journal 3: 555–569.

Kermode AR (2011) Plant storage products (carbohydrates, oils and proteins). In: eLS. Chichester: John Wiley & Sons, Ltd. DOI: 10.1002/9780470015902.a0001325.pub2.

Kim CS, Hunter BG, Kraft J, et al. (2004) A defective signal peptide in a 19‐kD alpha‐zein protein causes the unfolded protein response and an opaque endosperm phenotype in the maize De*‐B30 mutant. Plant Physiology 134: 380–387.

Kreis M, Forde BG, Rahman S, Miflin BJ and Shewry PR (1985) Molecular evolution of the seed storage proteins of barley, rye, and wheat. Journal of Molecular Biology 183 (3): 499–502.

Krishnan HB (2005) Engineering soybean for enhanced sulfur amino acid content. Crop Science 45 (2): 454–461.

Kuktaite R, Plivelic TS, Cerenius Y, et al. (2011) Structure and morphology of wheat gluten films: from polymeric protein aggregates toward superstructure arrangements. Biomacromolecules 12 (5): 1438–1448.

Marzabal P, Gas E, Fontanet P, et al. (2008) The maize Dof protein PBF activates transcription of gamma‐zein during maize seed development. Plant Molecular Biology 67 (5): 441–454.

Osborne TB (1924) The Vegetable Proteins. London: Longmans, Green and Co.

Pantoja‐Uceda D, Bruix M, Giménez‐Gallego G, et al. (2003) Solution structure of RicC3, a 2S albumin storage protein from Ricinus communis. Biochemistry 42 (47): 13839–13847.

Pysh LD, Aukerman MJ and Schmidt RJ (1993) OHP1‐ A maize basic domain leucine zipper protein that interacts with Opaque‐2. Plant Cell 5 (2): 227–236.

Rubio‐Somoza I, Martinez M, Abraham Z, Diaz I and Carbonero P (2006) Ternary complex formation between HvMYBS3 and other factors involved in transcriptional control in barley seeds. Plant Journal 47 (2): 269–281.

Schmidt RJ, Ketudat M, Aukerman MJ and Hoschek G (1992) Opaque‐2 is a transcriptional activator that recognizes a specific target site in 22‐kD zein genes. Plant Cell 4 (6): 689–700.

Shewry PR and Halford NG (2002) Cereal seed storage proteins: structures, properties and role in grain utilization. Journal of Experimental Botany 53 (370): 947–958.

Tan‐Wilson AL and Wilson KA (2012) Mobilization of seed protein reserves. Physiologia Plantarum 145 (1): 140–153.

Thompson RD, Hueros G, Becker H and Maitz M (2001) Development and functions of seed transfer cells. Plant Science 160 (5): 775–783.

Vicente‐Carbajosa J, Moose SP, Parsons RL and Schmidt RJ (1997) A maize zinc‐finger protein binds the prolamin box in zein gene promoters and interacts with the basic leucine zipper transcriptional activator Opaque2. Proceedings of the National Academy of Sciences of the United States of America 94 (14): 7685–7690.

Washida H, Kaneko S, Crofts N, et al. (2009) Identification of cis‐localization elements that target glutelin RNAs to a specific subdomain of the cortical endoplasmic reticulum in rice endosperm cells. Plant & Cell Physiology 50: 1710–1714.

Wobus U and Weber H (1999) Sugars as signal molecules in plant seed development. Biological Chemistry 380 (7–8): 937–944.

Wu YR and Messing J (2014) Proteome balancing of the maize seed for higher nutritional value. Frontiers in Plant Science 5: 240.

Xu JH and Messing J (2008) Organization of the prolamin gene family provides insight into the evolution of the maize genome and gene duplications in grass species. Proceedings of the National Academy of Sciences of the United States of America 105 (38): 14330–14335.

Zhang ZY, Yang J and Wu Y (2015) Transcriptional regulation of Zein Gene expression in maize through the additive and synergistic action of Opaque2, prolamine‐box binding factor, and O2 heterodimerizing proteins. Plant Cell 27 (4): 1162–1172.

Further Reading

Gutierrez L, Van Wuytswinkel O, Castelain M and Bellini C (2007) Combined networks regulating seed maturation. Trends in Plant Science 12 (7): 294–300.

Muntz K (1998) Deposition of storage proteins. Plant Molecular Biology 38 (1–2): 77–99.

Pedrazzini E, Mainieri D, Marrano CA, Vitale A, et al. (2016) Where do protein bodies of cereal seeds come from? Frontiers in Plant Science 7: 1139.

Reyes FC, Chung T, Holding D, et al. (2011) Delivery of prolamins to the protein storage vacuole in maize aleurone cells. Plant Cell 23 (2): 769–784.

Santos‐Mendoza M, Dubreucq B, Baud S, et al. (2008) Deciphering gene regulatory networks that control seed development and maturation in Arabidopsis. Plant Journal 54 (4): 608–620.

Washida H, Sugino A, Messing J, Esen A and Okita TW (2004) Asymmetric localization of seed storage protein RNAs to distinct subdomains of the endoplasmic reticulum in developing maize endosperm cells. Plant and Cell Physiology 45 (12): 1830–1837.

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Thompson, Richard D(Jun 2018) Storage Protein Synthesis. In: eLS. John Wiley & Sons Ltd, Chichester. [doi: 10.1002/9780470015902.a0023693]