The Biochemistry and Cell Biology of Embryo Storage Proteins

Abstract

Seed legumes accumulate massive amounts of certain characteristic proteins. These include the 7S and liS seed storage proteins, lectins and various 2S proteins. With the advent of molecular cloning techniques , a large and increasing number of primary structures of these proteins from many plants are available in the international databases. This review summarizes and compares sequences of the seed proteins presently available. To the extent that they are known, the genes which encode the proteins and mechanisms involved in their expression are summarized. Strategies involved in the assembly of the 7S and liS protein oligomers are discussed , and data that relate existing storage protein to their evolutionary progenitors are described .

Protein Storage Bodies and Vacuoles

“…In the past, the terms PB and PSV have been used interchangeably, but PSV is now used to differentiate vacuoles containing storage proteins from PBs originating from the ER. Our understanding of the cellular context in which storage proteins accumulate derives from many significant advances in gene structure and regulation, as well as the biochemistry and morphogenesis of storage tissues (reviewed in Chrispeels, 1991;Thomas, 1993;Staswick, 1994;Shewry et al, 1995;Galili and Herman, 1997;Nielsen et al, 1997;Shewry and Tatham, 1998; see also Battey et al, 1999;Marty, 1999;Sanderfoot and Raikhel, 1999;Vitale and Denecke, 1999, in this issue).…”

Cinnamomin, a type II ribosome-inactivating protein, is a storage protein in the seed of the camphor tree (Cinnamomum camphora)

“…However, arguments about the role of the ricin superfamily as seed storage proteins are unresolved [4,5,20,22]. Here we provide evidence that cinnamomin is a storage protein in C. camphora seeds.…”

“…Cinnamomin is one of the most prevalent proteins in C. camphora seeds, accounting for about 11 % of total proteins. This content is higher than many other storage proteins, such as soya bean 7 S basic storage proteins (5-10 %) and soya bean lipoxygenases (1-2 %) [22]. Most importantly, the amino acid composition of cinnamomin is very close to that of other storage proteins.…”

Molecular manipulation and modification of the genes encoding the G2 and G4 glycinin subunits

“…Glycinins are the predominant storage proteins in soybean seeds where they account for more than 20% of the seed dry weight in some cultivars and are primarily produced in cotyledon cells where they are sequestered within sub-cellular organelles called protein bodies (Nielsen el al., 1989;Nielsen et al, 1996;Nielsen and Nam, 1999;Vitale and Jurgen, 1999). As isolated from seed extracts, the glycinins are an oligomer of six similar subunits (Badley et al, 1975;Nielsen, 1996;Wang et al, 2003), the properties of which have been extensively reviewed (Moreira et al, 1979;Larkins, 1981;Turner et al, 1981;Chrispeels et al, 1982;Nielsen, 1984;Nielsen et al, 1996;Jung et al, 1998).…”

“…As isolated from seed extracts, the glycinins are an oligomer of six similar subunits (Badley et al, 1975;Nielsen, 1996;Wang et al, 2003), the properties of which have been extensively reviewed (Moreira et al, 1979;Larkins, 1981;Turner et al, 1981;Chrispeels et al, 1982;Nielsen, 1984;Nielsen et al, 1996;Jung et al, 1998).…”