Reference "Inhibition of UDP-glucose: protein transglucosylase by a maize endosperm protein factor"

Reference ID

8410

Title

Inhibition of UDP-glucose: protein transglucosylase by a maize endosperm protein factor

Source

Cellular and molecular biology (Noisy-le-Grand, France), 1996, vol. 42, pp. 645-651

Authors (4)

Rothschild-A	Wald-F-A
Bocca-S-N	Tandecarz-J-S

Abstract

UDP-glucose: protein transglucosylase (UPTG, EC 2.4.1.112) catalyzes the first
step of protein-bound alpha-glucan synthesis in potato tuber and developing
maize endosperm. The presence of a non-dialyzable, heat labile protein
responsible for low levels of UPTG activity in developing maize endosperm was
investigated. UPTG activity in 5-day old maize seedlings and potato tuber
solubilized preparations was also reduced by the endosperm preparation. FPLC-
Mono Q column chromatography of developing maize endosperm was effective in
separating the inhibitor protein (IP) from UPTG. After gel filtration on
Superose 12, IP yielded a major polypeptide of about 80 kDa on SDS-PAGE. IP was
purified by gel filtration on Superose 12 and preparative SDS-PAGE, and specific
antibodies were prepared. Polyclonal antibodies reacted specifically with an 80
kDa polypeptide of developing maize endosperm on Western blot. They also
recognized a similar band in 5-day old maize seedlings, but not in potato
tubers. The identification of a factor that regulates the level of UPTG activity
in developing maize endosperm may help to elucidate the functional role of the
enzyme in the initiation of starch synthesis during seed development.