PLANT PHYSIOLOGY , Vol 107, Issue 1 73-76, Copyright © 1995 by American Society of Plant Biologists
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CELL BIOLOGY AND SIGNAL TRANSDUCTION |
Polymerization of Actin from Maize Pollen
L. F. Yen, X. Liu and S. Cai
Laboratory of Plant Biochemistry, College of Biological Sciences, Beijing Agricultural University, Beijing 100094, China
Here we describe the in vitro polymerization of actin from maize (Zea mays)
pollen. The purified actin from maize pollen reported in our previous paper
(X. Liu, L.F. Yen [1992] Plant Physiol 99: 1151-1155) is biologically
active. In the presence of ATP, KCl, and MgCl2 the purified pollen actin
polymerized into filaments. During polymerization the spectra of absorbance
at 232 nm increased gradually. Polymerization of pollen actin was evidently
accompanied by an increase in viscosity of the pollen actin solution. Also,
the specific viscosity of pollen F-actin increased in a
concentration-dependent manner. The ultraviolet difference spectrum of
pollen actin is very similar to that of rabbit muscle actin. The activity
of myosin ATPase from rabbit muscle was activated 7-fold by the polymerized
pollen actin (F-actin). The actin filaments were visualized under the
electron microscope as doubly wound strands of 7 nm diameter. If
cytochalasin B was added before staining, no actin filaments were observed.
When actin filaments were treated with rabbit heavy meromyosin, the actin
filaments were decorated with an arrowhead structure. These results imply
that there is much similarity between pollen and muscle actin.
