Brady-Kalnay S M, Tonks N K
Cold Spring Harbor Laboratory, USA.
Curr Opin Cell Biol. 1995 Oct;7(5):650-7. doi: 10.1016/0955-0674(95)80106-5.
The intracellular segments of classic adhesion molecules such as N-CAM do not show structural similarity to any known signaling molecules. This suggests that their effects on signaling responses must be exerted indirectly through associated proteins. In contrast, many receptor protein tyrosine phosphatases (RPTPs) possess extracellular segments with homology to cell adhesion molecules linked directly to intracellular segments comprising one or two protein tyrosine phosphatase catalytic domains. Therefore, the RPTPs have the potential for direct modulation of catalytic function through engagement of the extracellular segment, suggesting they could be direct signal transducers of cell contact phenomena. In the past few years, some RPTPs have been shown to effect cell-cell adhesion directly via homophilic binding or indirectly by association with known cell adhesion molecules. In addition, RPTPs have been localized to points of cell-cell or cell-matrix contact, indicating their potential to regulate these structures.
诸如神经细胞黏附分子（N-CAM）等经典黏附分子的细胞内区段与任何已知的信号分子均无结构相似性。这表明它们对信号反应的影响必定是通过相关蛋白间接发挥作用的。相比之下，许多受体蛋白酪氨酸磷酸酶（RPTP）具有与细胞黏附分子同源的细胞外区段，这些区段直接与包含一个或两个蛋白酪氨酸磷酸酶催化结构域的细胞内区段相连。因此，RPTP有通过细胞外区段的结合直接调节催化功能的潜力，这表明它们可能是细胞接触现象的直接信号转导分子。在过去几年中，一些RPTP已被证明可通过同源性结合直接影响细胞间黏附，或通过与已知细胞黏附分子结合间接影响细胞间黏附。此外，RPTP已定位到细胞-细胞或细胞-基质接触点，表明它们有调节这些结构的潜力。
