|J Exp Bot 2003 Mar;54(384):913-22
Uncleaved legumin in developing maize endosperm: identification,
accumulation and putative subcellular localization.
Yamagata T, Kato H, Kuroda S, Abe S, Davies E.
Laboratory of Molecular Cell Biology, Department of Biological Resources, Faculty of
Agriculture, Ehime University, Matsuyama 790-8566, Japan. Botany Department, Box 7612,
North Carolina State University, Raleigh, NC 27695, USA.
While identifying proteins present in the cytoskeleton and protein body fractions from
maize (Zea mays L.) endosperm, a 51 kDa protein was discovered in a fraction containing
small ( approximately 200 nm in diameter) protein bodies. Based on partial amino acid
sequences of V8 protease fragments, degenerate primers were made and fragments of cDNA
encoding these partial sequences were cloned. Using 3' and 5' PCR, a full-length cDNA
encoding this 51 kDa protein was obtained, which was identified as legumin-1. In other
plants, this protein is generally cleaved into 20 and 35 kDa subunits after synthesis.
However, SDS-PAGE of both the native and denatured protein indicates that cleavage does
not occur in corn endosperm, even though the cleavage site (asparagine) is conserved. The
lack of cleavage is presumably because the canonical cleavage sequence downstream from the
cleavage site is almost totally absent. levels of transcript and encoded protein were
compared in all three varieties and it was shown that both are more abundant in wild-type
maize than in opaque-2 or sweet corn. Finally, using TEM, it was shown that the protein
apparently occurs in morphologically distinct protein bodies, very similar to the protein
bodies in legumes.
PMID: 12598562 [PubMed - in process]