Abstract:
:Calcium is essential for many biological processes involved in cellular motility. However, the pathway by which calcium influences motility, in processes such as muscle contraction and neuronal growth, is often indirect and complex. We establish a simple and direct mechanochemical link that shows how calcium quantitatively regulates the dynamics of a primitive motile system, the actin-based acrosomal bundle of horseshoe crab sperm. The extension of this bundle requires the continuous presence of external calcium. Furthermore, the extension rate increases with calcium concentration, but at a given concentration, we find that the volumetric rate of extension is constant. Our experiments and theory suggest that calcium sequentially binds to calmodulin molecules decorating the actin filaments. This binding leads to a collective wave of untwisting of the actin filaments that drives bundle extension.
journal_name
Biophys Jjournal_title
Biophysical journalauthors
Tam BK,Shin JH,Pfeiffer E,Matsudaira P,Mahadevan Ldoi
10.1016/j.bpj.2009.02.069subject
Has Abstractpub_date
2009-08-19 00:00:00pages
1125-9issue
4eissn
0006-3495issn
1542-0086pii
S0006-3495(09)00774-7journal_volume
97pub_type
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