The findings are in the Nov. 5 edition of the journal Molecular Cell and are online.
The protein, NaBC1, is found in most tissues and is part of a large family of ion transporting proteins that allow charged molecules to travel across cell membranes. Ion transporters are embedded in the cell membrane, opening and closing like gates to let charged ions and molecules enter and leave the cell. The movement of these molecules affects numerous essential cellular functions.
Like other nutrients, cells must transport boron across the membrane to control its concentration within the cell. The discovery of NaBC1 may help scientists understand how cells control internal boron concentration and the role of boron in a wide range of cellular processes, such as cell growth and bone mineralization.
"NaBC1 is very specific for the transport of borate, which is found in nearly everything we eat," said Dr. Shmuel Muallem, professor of physiology and the study's senior author.
Borate, the form of boron that the body uses, is essential for plant growth, pollination and crop size but until recently, no one knew how it entered plant cells. A borate transporter discovered in the plant Arabidopsis by another research group was shown to be very similar to human NaBC1.
Dr. Muallem, who had been studying NaBC1 in another context, hypothesized that NaBC1 was the human borate transporter.
"Since animals, including humans, get enough boron from our diets, it's hard to study the effect of boron deficiency in animal models and humans, but under conditions of malnutrition, there may be a strong effect of boron deficiency on embryonic development and, in adults, on bone maintenance and metabolic function," said
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Contact: Amanda Siegfried
amanda.siegfried@utsouthwestern.edu
214-648-3404
UT Southwestern Medical Center
4-Nov-2004