NASA Logo

NTRS

NTRS - NASA Technical Reports Server

Back to Results
Characterization of auxin-binding proteins from zucchini plasma membraneWe have previously identified two auxin-binding polypeptides in plasma membrane (PM) preparations from zucchini (Cucurbita pepo L.) (Hicks et al. 1989, Proc. Natl. Acad. Sci. USA 86, 4948-4952). These polypeptides have molecular weights of 40 kDa and 42 kDa and label specifically with the photoaffinity auxin analog 5-N3-7-3H-IAA (azido-IAA). Azido-IAA permits both the covalent and radioactive tagging of auxin-binding proteins and has allowed us to characterize further the 40-kDa and 42-kDa polypeptides, including the nature of their attachment to the PM, their relationship to each other, and their potential function. The azido-IAA-labeled polypeptides remain in the pelleted membrane fraction following high-salt and detergent washes, which indicates a tight and possibly integral association with the PM. Two-dimensional electrophoresis of partially purified azido-IAA-labeled protein demonstrates that, in addition to the major isoforms of the 40-kDa and 42-kDa polypeptides, which possess isoelectric points (pIs) of 8.2 and 7.2, respectively, several less abundant isoforms that display unique pIs are apparent at both molecular masses. Tryptic and chymotryptic digestion of the auxin-binding proteins indicates that the 40-kDa and 42-kDa polypeptides are closely related or are modifications of the same polypeptide. Phase extraction with the nonionic detergent Triton X-114 results in partitioning of the azido-IAA-labeled polypeptides into the aqueous (hydrophilic) phase. This apparently paradoxical behavior is also exhibited by certain integral membrane proteins that aggregate to form channels. The results of gel filtration indicate that the auxin-binding proteins do indeed aggregate strongly and that the polypeptides associate to form a dimer or multimeric complex in vivo. These characteristics are consistent with the hypothesis that the 40-kDa and 42-kDa polypeptides are subunits of a multimeric integral membrane protein which has an auxin-binding site, and which may possess transporter or channel function.
Document ID
20040112271
Acquisition Source
Headquarters
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Hicks, G. R.
(Oregon State University Corvallis 97331-2902, United States)
Rice, M. S.
Lomax, T. L.
Date Acquired
August 21, 2013
Publication Date
January 1, 1993
Publication Information
Publication: Planta
Volume: 189
Issue: 1
ISSN: 0032-0935
Subject Category
Life Sciences (General)
Funding Number(s)
CONTRACT_GRANT: DCB 8904114
CONTRACT_GRANT: NAGW-1253
CONTRACT_GRANT: NGT5-0455
Distribution Limits
Public
Copyright
Other
Keywords
NASA Program Space Biology
Non-NASA Center
NASA Discipline Plant Biology
NASA Discipline Number 40-50

Available Downloads

There are no available downloads for this record.
No Preview Available