Plant Molecular Biology 38: 481–490, 1998.
© 1998 Kluwer Academic Publishers. Printed in the Netherlands.
Tissue- and stage-speciﬁc expression of a soybean (Glycine max L.)
seed-maturation, biotinylated protein
Yue-ie C. Hsing
, Chih-hua Tsou
, Tze-fu Hsu
, Zuey-ying Chen
, Kim-leong Hsieh
and Teh-yuan Chow
Institute of Botany, Academia Sinica, Taipei, Taiwan (
author for correspondence);
Department of Agronomy,
National Taiwan University, Taipei, Taiwan
Received 21 October 1997; accepted in revised form 8 April 1998
Key words: developmental expression, localization, recombinant protein, seed maturation
A cDNA clone GmPM4 which encodes mRNA species in mature or dry soybean seeds was characterized. DNA
sequence analysis shows that the deduced polypeptides have a molecular mass of 68 kDa. GmPM4 proteins have a
relatively high amino acid sequence homology with a major biotinylated protein isolated from pea seeds, SBP65,
but both of these proteins differ markedly from that of presently known biotin enzymes. The accumulation of
GmPM4 mRNA is detectable in the leaf primodium and the vascular tissues of the hypocotyl-radicleaxis of mature
seeds, and the GmPM4 proteins are present at high levels in dry and mature soybean seeds, but not in fresh
immature seeds. It degrades rapidly at the early stage of seed germination. These proteins are boiling-soluble
and biotinylated when they are present endogenously in soybean seeds; however, the same recombinant protein
expressed in Escherichia coli is boiling-soluble, but it is not biotinylated.
Late maturation of seeds is marked not only by water
loss but also by a drastic change in proﬁle of proteins
synthesized [e.g. 31]. Proteins synthesized during this
late stage, which are correlated with desiccation toler-
ance , ABA content , or transition to seedling
growth , are often termed maturation proteins 
or late embryogenesis-abundant (LEA) proteins .
Maturation proteins are slightly different from LEA
proteins in that the messages for maturation proteins
are not necessarily present at a relatively high level
as LEA message during late embryogenesis. Based on
the commonly shared amino acid sequence domains,
LEA proteins are grouped into three or four groups
[8, 9]. Virtually all of the LEA proteins are highly
hydrophilic, contain no Cys or Trp residues, and are
boiling-soluble [8, 9]. It has been hypothesized that
The nucleotide sequence data reported will appear in the
EMBL, GenBank and DDBJ Nucleotide Sequence Databases under
the accession number U59626.
LEA proteins may play a protective role in plant cell
under various stress conditions and this protective role
may be essential for the survival of the plant under
extreme stress conditions [9, 37].
We have isolated a number of cDNA clones of
soybean seed maturation proteins from a pod-dried
seed cDNA library by differential screening [23, 24].
These are designated GmPM clones, denoting for
Glycine max physiologically mature. pGmPM1 
and pGmPM9  were found as a member of the
group 4 LEA family, and pGmPM2 , pGmPM8
and pGmPM10  group 3 LEA family.
In the present study, we report the identiﬁcation
and characterization of a novel soybean seed matura-
tion protein and its cDNA clone, GmPM4. We show
that the GmPM4 protein is biotinylated. We investi-
gated the cellular and tissue localization of the RNA
transcripts and the expression of this protein during
seed development and germination. We also charac-
terized the biochemical behaviors of the recombinant
plant GmPM4 proteins in E. coli.