Nuclear titin interacts with histones.
BACKGROUND
Titin is a giant muscle protein that is responsible for the elasticity of muscle and may also function as a molecular scaffold for myofibrillar assembly. However, its presence in the nucleus remains elusive.


METHODS
Nuclear titin was extracted with 0.15 M sodium phosphate buffer containing 0.3 M NaCl, followed by ammonium sulfate fractionation and gel filtration column chromatography. The proteins not separable from titin were subjected to mass spectrometry (MS) and MS/MS analyses.


RESULTS
This purification procedure removed almost all impurities except three low molecular weight proteins (12-15 kDa). These proteins were not separated from titin through various types of column chromatography, indicating their strong interaction with nuclear titin. These proteins were identified as histones H2A, H3 and H4 by MS and MS/MS analyses.


CONCLUSIONS
The existence of titin in the nucleus was confirmed by obtaining purified titin from the nucleus. Furthermore, nuclear titin exhibited strong interaction with histones H2A, H3 and H4, suggesting its role as a chromosome scaffold.
King
Lan
L
Department of Biochemistry and Molecular Biology, Collage of Medicine, Chang Gung University, Taoyuan, Taiwan. lanking@mail.cgu.edu.tw
Jhou
Chun-Ru
CR
D064211:Connectin; D006657:Histones / Q000378:metabolism*; D006801:Humans; D009124:Muscle Proteins / Q000302:isolation & purification / Q000378:metabolism*; D011494:Protein Kinases / Q000302:isolation & purification / Q000378:metabolism*
D064211:Connectin; D006657:Histones; D009124:Muscle Proteins; C577285:TTN protein, human; D011494:Protein Kinases