Reference "Identification of a UPTG inhibitor protein from maize endosperm: high homology with sucrose synthase protein"

Reference ID

8411

Title

Identification of a UPTG inhibitor protein from maize endosperm: high homology with sucrose synthase protein

Source

Cellular and molecular biology (Noisy-le-Grand, France), 1998, vol. 44, pp. 397-406

Authors (4)

Wald-F-A	Rothschild-A
Moreno-S	Tandecarz-J-S

Abstract

A thermolabile UPTG inhibitor protein (IP) was isolated and purified from a
developing maize endosperm preparation. High homology of two internal peptides
of IP with known plant sucrose synthase (SS) sequences suggested that IP might
be related somehow with SS. IP and SS activities were found in the same
preparation and showed thermolability between 60-65 degrees C. IP and SS
activities presented the same ionic charge and molecular mass in native
conditions (Mono Q and Superose-12 columns chromatographies). Western blot
experiments with an anti-SS antibody as well as with an anti-IP antibody showed
a single 80 kDa polypeptide band where IP and SS activities were present. Anti-
SS antibody can neutralize SS as well as IP activities in a neutralization
assay. It was found that in the maize mutant shrunken-1, lacking SS1 protein,
the UPTG activity was not inhibited. Furthermore, the solubilized preparation of
the sh1 endosperm is unable of inhibiting UPTG activity from potato tuber. The
high correlation between IP and SS properties suggests that IP might be in fact
a form of SS. Moreover, the relation between IP and the SS1 isoform is
discussed. So, a new biological activity of SS is suggested.