actin in the nuclear

actin还真是到处都是，上次那个矮个老头来我们这边讲，我还没怎么在意，因为data相对不是很吸引人。但好歹是zina以前的老板。今天一看，居然actin myosinI的故事是一篇2000的science，而且2004一帮人说了actin和transcription有作用。hoho，蛋白量大了，功能相对也多。可谓能者多劳，多劳多产，多产再多能……

Science 13 October 2000:
Vol. 290. no. 5490, pp. 337 - 341
A Myosin I Isoform in the Nucleus

A nuclear isoform of myosin I beta that contains a unique 16-amino acid amino-terminal extension has been identified. An affinity-purified antibody to the 16-amino acid peptide demonstrated nuclear staining. Confocal and electron microscopy revealed that nuclear myosin I beta colocalized with RNA polymerase II in an alpha -amanitin- and actinomycin D-sensitive manner. The antibody coimmunoprecipitated RNA polymerase II and blocked in vitro RNA synthesis. This isoform of myosin I beta appears to be in a complex with RNA polymerase II and may affect transcription.

Department of Physiology and Biophysics, University of Illinois at Chicago, Chicago, IL 60612, USA.
To whom correspondence should be addressed. E-mail: primal@uic.edu, Primal de Lanerolle1dagger

http://www.nature.com/embor/journal/v6/n3/fig_tab/7400362_f1.html

Actin and nuclear myosin 1 in transcription by RNA polymerase I. Actin is directly associated with RNA polymerase I (Pol I), regardless of whether Pol I is engaged in transcription, and nuclear myosin 1 (NM1) interacts with transcription initiation factor TIF-IA. Extracellular mitogens activate signalling cascades that lead to TIF-IA phosphorylation. Pol I is then recruited to the ribosomal DNA promoter through interaction with the phosphorylated TIF-IA, which brings actin and NM1 into close proximity with each other. Actin, but not NM1, remains associated with Pol I during transcription elongation.