Direct photolabeling with [32P]UDP-glucose for identification of a subunit of cotton fiber callose synthase

Deborah P. Delmer, Mazal Solomon, Stephen M. Read

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60 Scopus citations

Abstract

We have identified a 52 kilodalton polypeptide as being a likely candidate for the catalytic subunit of the UDP-glucose: (1→3)-β-glucan (callose) synthase of developing fibers of Gossypium hirsutum (cotton). Such a polypeptide migrates coincident with callose synthase during glycerol gradient centrifugation in the presence of EDTA, and can be directly photolabeled with the radioactive substrate, α-[32P]UDP-glucose. Interaction with the labeled probe requires Ca2+, a specific activator of callose synthase which is known to lower the Km of higher plant callose synthases for the substrate UDP-glucose. Using this probe and several other related ones, several other proteins which interact with UDP-glucose were also identified, but none satisfied all of the above criteria for being components of the callose synthase.

Original languageEnglish
Pages (from-to)556-563
Number of pages8
JournalPlant Physiology
Volume95
Issue number2
DOIs
StatePublished - Feb 1991

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