Plasma membrane intrinsic proteins of Beta vulgaris L

Plasma membrane intrinsic proteins of Beta vulgaris L

1995

A:PS

The plasma membrane (PM) of higher plants contains numerous proteins; however, due to their low abundance, only a few have been identified and characterized by direct biochemical approaches. The major intrinsic protein (MIP) family is a class of highly hydrophobic integral membrane proteins thought to function as channels that facilitate the passage of water, small solutes and possibly other moieties through the membrane. A family of PM intrinsic proteins was purified and characterized from PM vesicles derived from storage tissue of beetroot using the detergent 3-((3-cholamidopropyl)dimethylammonio)-1-propane sulfonate. This PM intrinsic protein-enriched fraction also contained high levels of UDP-glucose:(1,3)-beta-glucan (callose) synthase activity. Dithiothreitol was required to visualize the monomeric species of these highly hydrophobic integral membrane proteins. Sequence analysis of tryptic fragments derived from polypeptides of 31 and 27 kDa revealed significant homologies to plant MIPs identified from cloned sequences. These MIPs included clone 7a from pea and RD28 from Arabidopsis, both of which are water-stress proteins, a tomato ripening-associated membrane protein, and PIP 2b, a PM-bound water channel protein from Arabidopsis. MIPs, therefore, represent abundantly occurring components of PMs derived from beet storage tissue.

v.108(1):387-392, PLANT PHYSIOLOGY

Research > Published Articles