O'Neal K D, Yu-Lee L Y
Department of Microbiology and Immunology, Baylor College of Medicine, Houston, TX 77030.
Lymphokine Cytokine Res. 1993 Oct;12(5):309-12.
Members of the cytokine receptor superfamily have been grouped together by function and by the presence of conserved amino acids in the extracellular domain, including four cysteine residues and the Trp-Ser-X-Trp-Ser (WSXWS) motif. However, no consensus sequence motif has been described in the intracellular domain of the cytokine receptors. We now report the presence of a proline-rich consensus sequence motif, eight amino acids in length, which is found in the intracellular domain of all the cytokine receptors. The proline-rich motif (PRM) can be divided into two complementary families that have superimposable consensus sequences. The consensus sequences were found by allowing similar amino acids (aliphatic = Al, aromatic = Ar) to be grouped together. The first motif (PRM1) has the sequence Al-Ar-Pro-X-Al-Pro-X-Pro, while the second (PRM2) is Ar-X-X-X-Al-Pro-X-Pro. An overall consensus sequence for the PRM (PRM1 and PRM2) is derived by allowing aromatic and aliphatic residues to be considered hydrophobic (psi): psi-X-X-X-Al-Pro-X-Pro. Several alternative cytokine receptor isoforms contain two copies of the PRM within the same intracellular domain. The conservation of the proline-rich motif in cytokine receptors suggests that it plays a critical role in receptor function and defines a new feature of the cytokine receptor superfamily.
细胞因子受体超家族的成员已根据功能以及细胞外结构域中保守氨基酸的存在情况进行了归类，这些保守氨基酸包括四个半胱氨酸残基以及色氨酸 - 丝氨酸 - X - 色氨酸 - 丝氨酸（WSXWS）基序。然而，细胞因子受体的细胞内结构域中尚未描述出一致的序列基序。我们现在报告在所有细胞因子受体的细胞内结构域中发现了一个富含脯氨酸的一致序列基序，其长度为八个氨基酸。富含脯氨酸的基序（PRM）可分为两个互补的家族，它们具有可叠加的一致序列。这些一致序列是通过允许相似的氨基酸（脂肪族 = Al，芳香族 = Ar）归为一组而发现的。第一个基序（PRM1）的序列为Al - Ar - Pro - X - Al - Pro - X - Pro，而第二个（PRM2）是Ar - X - X - X - Al - Pro - X - Pro。通过允许芳香族和脂肪族残基被视为疏水性（psi），得出了PRM（PRM1和PRM2）的总体一致序列：psi - X - X - X - Al - Pro - X - Pro。几种替代性细胞因子受体亚型在同一细胞内结构域中包含两个PRM拷贝。细胞因子受体中富含脯氨酸基序的保守性表明它在受体功能中起关键作用，并定义了细胞因子受体超家族的一个新特征。
