Edgar A J, Knight A E, Bennett J P
Department of Anatomy and Cell Biology, Imperial College School of Medicine at St Mary's, London, UK.
J Anat. 1996 Oct;189 ( Pt 2)(Pt 2):451-6.
Little is known about the functions of members of the myosin I family in vertebrates. Chicken myosin IB is a member of the amoeba-type subclass of myosin I molecules and tissue localisation studies may provide possible clues to the functions of these myosin I molecules. The expression of the mRNA of this unconventional myosin IB was analysed by in situ hybridization and compared with that of the well characterised brush border myosin I on frozen sections of tissues from the adult domestic chicken. High levels of myosin IB mRNA were found in the intestine and spleen, but were not found in other tissues examined such as brain, heart, lung, liver and kidney. In the intestine, myosin IB mRNA was much more abundant in the lamina propria than in the enterocytes, whereas brush border myosin I mRNA was restricted to the enterocytes. In the spleen, myosin IB mRNA expression was abundant in regions of white pulp, namely germinal centres, periellipsoid lymphocyte sheaths and periarteriolar lymphocyte sheaths. Lymphocytes are the major cell type in both the lamina propria and the white pulp of the spleen, which suggests that chicken myosin IB is highly expressed in lymphocytes. Lymphocyte recirculation depends on their migration through the endothelial layer and it is possible that myosin IB may have a role to play in this type of cell motility.
关于脊椎动物中肌球蛋白I家族成员的功能，人们了解甚少。鸡肌球蛋白IB是肌球蛋白I分子的变形虫型亚类的成员，组织定位研究可能为这些肌球蛋白I分子的功能提供线索。通过原位杂交分析了这种非常规肌球蛋白IB的mRNA表达，并与成年家鸡组织冰冻切片上特征明确的刷状缘肌球蛋白I的mRNA表达进行了比较。在肠道和脾脏中发现了高水平的肌球蛋白IB mRNA，但在其他检测的组织如脑、心脏、肺、肝脏和肾脏中未发现。在肠道中，肌球蛋白IB mRNA在固有层比在肠细胞中丰富得多，而刷状缘肌球蛋白I mRNA仅限于肠细胞。在脾脏中，肌球蛋白IB mRNA在白髓区域大量表达，即生发中心、椭球周围淋巴细胞鞘和动脉周围淋巴细胞鞘。淋巴细胞是脾脏固有层和白髓中的主要细胞类型，这表明鸡肌球蛋白IB在淋巴细胞中高度表达。淋巴细胞再循环取决于它们穿过内皮细胞层的迁移，肌球蛋白IB可能在这种类型的细胞运动中发挥作用。
