Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona, USA.
Department of Chemistry and Biochemistry, University of Arizona, Tucson, Arizona, USA.
J Biol Chem. 2024 Jun;300(6):107333. doi: 10.1016/j.jbc.2024.107333. Epub 2024 May 22.
The human Solute Carrier (SLC) family member, monocarboxylate transporter 1 (MCT1), transports lactic and pyruvic acid across biological membranes to regulate cellular pH and metabolism. Proper trafficking of MCT1 from the endoplasmic reticulum to the plasma membrane hinges on its interactions with the membrane-bound chaperone protein, CD147. Here, using AlphaFold2 modeling and copurification, we show how a conserved signature motif located in the flexible N-terminus of MCT1 is a crucial region of interaction between MCT1 and the C-terminus of CD147. Mutations to this motif-namely, the thymic cancer linked G19C and the highly conserved W20A-destabilize the MCT1-CD147 complex and lead to a loss of proper membrane localization and cellular substrate flux. Notably, the monomeric stability of MCT1 remains unaffected in mutants, thus supporting the role of CD147 in mediating the trafficking of the heterocomplex. Using the auxiliary chaperone, GP70, we demonstrated that W20A-MCT1 can be trafficked to the plasma membrane, while G19C-MCT1 remains internalized. Overall, our findings underscore the critical role of the MCT1 transmembrane one signature motif for engaging CD147 and identify altered chaperone binding mechanisms between the CD147 and GP70 glycoprotein chaperones.
人类溶质载体 (SLC) 家族成员单羧酸转运蛋白 1 (MCT1) 将乳酸和丙酮酸跨生物膜转运，以调节细胞 pH 值和代谢。MCT1 从内质网正确转运到质膜取决于其与膜结合伴侣蛋白 CD147 的相互作用。在这里，我们使用 AlphaFold2 建模和共纯化，展示了位于 MCT1 灵活的 N 端的保守特征基序如何成为 MCT1 和 CD147 C 端之间相互作用的关键区域。该基序的突变——即胸腺癌相关的 G19C 和高度保守的 W20A——破坏了 MCT1-CD147 复合物，导致正确的膜定位和细胞底物通量丧失。值得注意的是，突变体中 MCT1 的单体稳定性保持不变，这支持了 CD147 在介导异质复合物运输中的作用。使用辅助伴侣蛋白 GP70，我们证明了 W20A-MCT1 可以被转运到质膜，而 G19C-MCT1 仍然被内化。总的来说，我们的发现强调了 MCT1 跨膜一特征基序对于与 CD147 结合的关键作用，并确定了 CD147 和 GP70 糖蛋白伴侣之间改变的伴侣结合机制。
