Smith M J, Koch G L
MRC Laboratory of Molecular Biology, Cambridge, UK.
EMBO J. 1989 Dec 1;8(12):3581-6. doi: 10.1002/j.1460-2075.1989.tb08530.x.
The complete amino acid sequence of CRP55, the major 55 kd calcium binding protein of the ER lumen, was deduced from the murine cDNA nucleotide sequence. This was completed using a novel application of PCR amplification. The mature 399 residue protein encoded is preceded by a 17 amino acid leader sequence and ends in the ER signal sequence, KDEL. The protein contains no calcium binding motifs of the EF hand type or of the form seen in calelectrin-related proteins. The major region of potential low affinity calcium binding sites is a polyacidic stretch towards the C terminus. The primary structure of the protein is markedly zonal. The N-terminal region, of approximately neutral net charge and hydrophobicity, is followed by a central proline-rich zone with repeat sequences separated from the polyacidic C-terminal stretch by a short hydrophobic sequence. The general shape suggested is a globular domain attached to an extended tail. Immunofluorescence studies show that the protein is present in skeletal muscle and indicate that it is a sarcoplasmic reticulum protein. We propose that the protein be named calreticulin to reflect its calcium binding activity and location in the ER and SR.
通过小鼠cDNA核苷酸序列推导得出内质网腔中主要的55kd钙结合蛋白CRP55的完整氨基酸序列。这是利用PCR扩增的一种新应用完成的。所编码的成熟的399个残基的蛋白质之前有一个17个氨基酸的前导序列，并以内质网信号序列KDEL结尾。该蛋白质不包含EF手型或在钙电蛋白相关蛋白质中所见形式的钙结合基序。潜在的低亲和力钙结合位点的主要区域是朝向C末端的多酸性片段。该蛋白质的一级结构明显呈区域化。N末端区域具有大约中性的净电荷和疏水性，接着是一个富含脯氨酸的中央区域，其重复序列通过一个短的疏水序列与多酸性的C末端片段分开。所推测的总体形状是一个附着在延伸尾部的球状结构域。免疫荧光研究表明该蛋白质存在于骨骼肌中，并表明它是一种肌浆网蛋白。我们建议将该蛋白质命名为钙网蛋白，以反映其钙结合活性以及在内质网和肌浆网中的定位。
