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在正常生理状态下,真核细胞内Ca~(2+)浓度为10~(-7)～10~(-6)mol/L,细胞外侧为10~(-3)mol/L,即细胞膜的两侧存在1000～10000倍的跨膜Ca~(2+)梯差。当细胞外信息跨膜传递时细胞外Ca~(2+)内流,胞浆中的Ca~(2+)浓度升高,细胞膜两侧的跨膜Ca~(2+)梯差降低约10倍,即膜内外两侧的跨膜Ca~(2+)梯差为100倍;而信息传递完成后胞浆中的Ca~(2+)会通过质膜上的Ca~(2+)-ATP酶或Na~+-Ca~(2+)交换运出细胞外以维持膜两侧合适的跨膜Ca~(2+)梯差。因此,细胞膜两侧的跨膜Ca~(2+)梯差在维持细胞正常功能中具有重要的生理意义。但这种跨膜Ca~(2+)梯差对膜结合蛋白,尤其是对参与构成信息跨膜转导体系的膜蛋白的结构与功能及其相互作用的影响尚未引起足够的重视。
Under normal physiological conditions, the concentration of Ca 2+ in eukaryotic cells was 10 -7 -7 10 -6 mol / L, and the extracellular level was 10 -3 mol / L, There are 1000 ~ 10000 times the transmembrane Ca ~ (2 +) ladder on both sides. When extracellular Ca2 + translocated, extracellular Ca2 + influx increased Ca2 + concentration in the cytoplasm, and the transmembrane Ca2 + gradient on both sides of the cell membrane decreased about 10 Fold, that is, the transmembrane Ca ~ (2 +) ladder at both the inside and outside of the membrane is 100-fold. When the information is delivered, the Ca ~ (2+) in the cytoplasm will pass through Ca ~ (2 +) - ATPase or Na ~ + -Ca ~ (2+) exchange out of the cell in order to maintain the appropriate transmembrane Ca ~ (2 +) ladder on both sides of the membrane. Therefore, the transmembrane Ca2 + ladder on both sides of the cell membrane has important physiological significance in maintaining the normal function of cells. However, the effect of this transmembrane Ca 2+ ladder on the structure and function of membrane-bound proteins, especially on the structure and function of membrane proteins involved in the information transmembrane transduction system and their interactions has not been given enough attention.