Harpaz Y, Chothia C
Cambridge Centre for Protein Engineering, U.K.
J Mol Biol. 1994 May 13;238(4):528-39. doi: 10.1006/jmbi.1994.1312.
On the basis of similarities in sequence and structure, the protein domains that form the immunoglobulin superfamily have been divided into three sets: one with variable-like domains, the V set, and two with different variants of the constant-like domains, the C1 and C2 sets. Examination of a muscle member of the immunoglobulin superfamily, telokin, shows that its structure is closely related to those of the variable domains found in antibodies, CD2, CD4 and CD8. However, it also contains structural features that, previously, have only been found in constant domains. Telokin represents a new structural set in the superfamily which we call the I set. Using the structures of telokin, and variable domains from antibodies, CD4 and CD8, we constructed a profile that describes the sequence characteristics of the structural core common to those proteins. This sequence profile makes a good match to the sequences of many of the immunoglobulin superfamily domains that form the cell adhesion molecules and surface receptors. This match implies that these domains also have structures that belong to the I set.
基于序列和结构的相似性，构成免疫球蛋白超家族的蛋白质结构域已被分为三类：一类具有可变样结构域，即V类；另外两类具有不同变体的恒定样结构域，即C1类和C2类。对免疫球蛋白超家族的一个肌肉成员——端激酶的研究表明，其结构与抗体、CD2、CD4和CD8中发现的可变结构域密切相关。然而，它还包含以前仅在恒定结构域中发现的结构特征。端激酶代表了超家族中的一个新结构类，我们称之为I类。利用端激酶的结构以及抗体、CD4和CD8的可变结构域，我们构建了一个描述这些蛋白质共有的结构核心序列特征的图谱。该序列图谱与许多构成细胞粘附分子和表面受体的免疫球蛋白超家族结构域的序列匹配良好。这种匹配意味着这些结构域也具有属于I类的结构。
