Kjellgren Daniel, Stål Per, Larsson Lars, Fürst Dieter, Pedrosa-Domellöf Fatima
Department of Clinical Sciences, Ophthalmology, Umeå University, Umeå, Sweden; the.
Invest Ophthalmol Vis Sci. 2006 Oct;47(10):4188-93. doi: 10.1167/iovs.05-1496.
To examine the distribution of myosin-binding protein C (MyBP-C) in human extraocular muscles (EOMs) and to correlate the myosin heavy chain (MyHC) and the MyBP-C composition of the fibers.
Samples from 17 EOMs, 3 levator palpebrae (LP), and 6 limb muscles were analyzed with SDS-PAGE and immunoblot or processed for immunocytochemistry with monoclonal antibodies (mAbs) against MyBP-C-fast, MyBP-C-slow, MyHCIIa, MyHCI, MyHCsto, MyHCalpha-cardiac, and MyHCemb.
In the limb muscle samples, fast fibers were labeled with anti-MyBP-C-fast and anti-MyBP-C-slow, whereas the slow fibers were immunostained with anti-MyBP-C-slow only, in accordance with previous studies. In 11 EOM samples MyBP-C-fast was not detected, and weak staining with anti-MyBP-C-fast was seen only in a few fibers in the proximal part of 2 muscles. The mAb against MyBP-C-slow labeled all fibers, but fibers containing MyHCI were generally more strongly stained. In the levator palpebrae, immunostaining with anti-MyBP-C-fast was present in some fibers labeled with anti-MyHCIIa and/or anti-MyHCeom. MyBP-C-fast and -intermediate were not detected biochemically in the EOMs.
The lack of MyBP-C-fast and intermediate is an additional feature of the human EOM allotype. The true EOMs have a unique myofibrillar protein isoform composition reflecting their special structural and functional properties. The levator palpebrae muscle phenotype is intermediate between that of the EOMs and the limb muscles.
研究肌球蛋白结合蛋白C（MyBP-C）在人眼外肌（EOMs）中的分布，并将纤维的肌球蛋白重链（MyHC）与MyBP-C组成进行关联。
采用十二烷基硫酸钠-聚丙烯酰胺凝胶电泳（SDS-PAGE）和免疫印迹法分析17条眼外肌、3条提上睑肌（LP）和6条肢体肌肉的样本，或用抗MyBP-C-fast、MyBP-C-slow、MyHCIIa、MyHCI、MyHCsto、MyHCalpha-心脏型和MyHCemb的单克隆抗体（mAbs）进行免疫细胞化学处理。
在肢体肌肉样本中，快肌纤维用抗MyBP-C-fast和抗MyBP-C-slow标记，而慢肌纤维仅用抗MyBP-C-slow免疫染色，与先前研究一致。在11个眼外肌样本中未检测到MyBP-C-fast，仅在2条肌肉近端的少数纤维中观察到抗MyBP-C-fast的弱染色。抗MyBP-C-slow的单克隆抗体标记了所有纤维，但含有MyHCI的纤维通常染色更强。在提上睑肌中，抗MyBP-C-fast的免疫染色存在于一些用抗MyHCIIa和/或抗MyHCeom标记的纤维中。在眼外肌中未通过生化方法检测到MyBP-C-fast和中间型。
缺乏MyBP-C-fast和中间型是人类眼外肌异型的另一个特征。真正的眼外肌具有独特的肌原纤维蛋白异构体组成，反映了它们特殊的结构和功能特性。提上睑肌的表型介于眼外肌和肢体肌肉之间。
