Saturation mutagenesis was performed on a single position in the voltage-sensing domain (VSD) of a genetically encoded voltage indicator (GEVI). The VSD consists of four transmembrane helixes designated S1-S4. The V220 position located near the plasma membrane/extracellular interface had previously been shown to affect the voltage range of the optical signal. Introduction of polar amino acids at this position reduced the voltage-dependent optical signal of the GEVI. Negatively charged amino acids slightly reduced the optical signal by 33 percent while positively charge amino acids at this position reduced the optical signal by 80%. Surprisingly, the range of V220D was similar to that of V220K with shifted optical responses towards negative potentials. In contrast, the V220E mutant mirrored the responses of the V220R mutation suggesting that the length of the side chain plays in role in determining the voltage range of the GEVI. Charged mutations at the 219 position all behaved similarly slightly shifting the optical response to more negative potentials. Charged mutations to the 221 position behaved erratically suggesting interactions with the plasma membrane and/or other amino acids in the VSD. Introduction of bulky amino acids at the V220 position increased the range of the optical response to include hyperpolarizing signals. Combining The V220W mutant with the R217Q mutation resulted in a probe that reduced the depolarizing signal and enhanced the hyperpolarizing signal which may lead to GEVIs that only report neuronal inhibition.
Amino Acids ; Cell Membrane ; Fluorescence ; Mutagenesis ; Neurons ; Plasma

Objective To know about the status of hypertension among Mongolian and Han aged older than 55 years living in pastoral area of the Inner Mongolia Autonomous Region.Methods Stratified sampling method was adopted and 9146 people aged 55 years or older were selected,blood pressure measurement and related information were collected,prevalence,awareness,treatment and control rates of hypertension were analyzed.Results The hypertension crude prevalence rate of Mongolian and Han subjects was 54.10％ ( standardized prevalence rate was 53.93％ ),in which,the Mongolian and Han subjects crude hypertension prevalence rate was 52.96％ and 54.73％ respectively (standardized prevalence rate was 53.44％ and 55.08％ respectively),and there was no statistically significant ( P =0.104).Among the male gender,awareness rate,treatment rate and control rate of hypertension was 61.03％,46.73％ and 11.87％ respectively.Among the female gender, awareness rate, treatment rate and control rate of hypertension was 67.58％,56.55％ and 14.03％ respectively.Among Mongolian and Han subjects,difference of hypertension prevalence of different age groups was statistically significant( P values were 0.032 and 0.000),Among Mongolian subjects,difference of hypertension awareness of different age groups was statistically significant ( P =0.000 ).Among Han subjects,difference of hypertension awareness rates,treatment rates,and control rates of different age groups were statistically significant( P values were 0.000,0.047 and 0.043 ).Conclusion Hypertension prevalence rate among Han and Mongolian people older than 55 years living in pastoral area of Inner Mongolia Autonomous Region is high while the awareness,treatment and control rates of hypertension are rather low.