Medeiros N A, Reese T S, Jaffe H, Degiorgis J A, Bearer E L
Department of Pathology and Laboratory Medicine, Brown University, Providence, RI, 02912, USA.
Cell Biol Int. 1998;22(2):161-73. doi: 10.1006/cbir.1998.0248.
The squid giant axon provides an excellent model system for the study of actin-based organelle transport likely to be mediated by myosins, but the identification of these motors has proven to be difficult. Here the authors purified and obtained primary peptide sequence of squid muscle myosin as a first step in a strategy designed to identify myosins in the squid nervous system. Limited digestion yielded fourteen peptides derived from the muscle myosin which possess high amino acid sequence identities to myosin II from scallop (60-95%) and chick pectoralis muscle (31-83%). Antibodies generated to this purified muscle myosin were used to isolate a potential myosin from squid optic lobe which yielded 11 peptide fragments. Sequences from six of these fragments identified this protein as a myosin II. The other five sequences matched myosin II (50-60%, identities), and some also matched unconventional myosins (33-50%). A single band that has a molecular weight similar to the myosin purified from optic lobe copurifies with axoplasmic organelles, and, like the optic lobe myosin, this band is also recognized by the antibodies raised against squid muscle myosin II. Hence, this strategy provides an approach to the identification of a myosin associated with motile axoplasmic organelles.
乌贼巨大轴突为研究可能由肌球蛋白介导的基于肌动蛋白的细胞器运输提供了一个出色的模型系统，但事实证明，鉴定这些分子马达具有挑战性。在本文中，作者纯化并获得了乌贼肌肉肌球蛋白的一级肽序列，这是旨在鉴定乌贼神经系统中肌球蛋白的策略的第一步。有限酶切产生了14个源自肌肉肌球蛋白的肽段，这些肽段与扇贝的肌球蛋白II（60-95%）和鸡胸肌的肌球蛋白II（31-83%）具有高度的氨基酸序列同一性。针对这种纯化的肌肉肌球蛋白产生的抗体被用于从乌贼视叶中分离出一种潜在的肌球蛋白，该肌球蛋白产生了11个肽片段。其中6个片段的序列将该蛋白质鉴定为肌球蛋白II。其他5个序列与肌球蛋白II匹配（同一性为50-60%），并且有些还与非常规肌球蛋白匹配（33-50%）。一条分子量与从视叶纯化的肌球蛋白相似的条带与轴浆细胞器共纯化，并且与视叶肌球蛋白一样，这条带也被针对乌贼肌肉肌球蛋白II产生的抗体识别。因此，该策略提供了一种鉴定与可移动轴浆细胞器相关的肌球蛋白的方法。
