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Table 1 Key amino acid positions, linkers and in vitro Ca2+ response of cpFP-based Ca2+ sensors. Linker sites: linkers connecting M13 with cpFP and cpFP with calmodulin. cpFP is underlined, positions 148 and 145 are shown in bold. Data for Part A are from literature. See Methods section for the details concerning proteins purification and spectroscopy for Parts B and C

From: Single fluorescent protein-based Ca2+sensors with increased dynamic range

Sensor Linker sites 148 145 203 Maximum fluorescence response to Ca2+, fold, comments
Part A: previously developed sensors
Pericam YNS H NVY---LEYN G TGDQ H G Y 3,0 × increase
Flash-periam YNS H NVY---LEYN G TGDQ H G H 8,0 × increase low pH stability
Ratiometric-pericam YNS D NVY---LEYN G TDQL D G F 10,0 × ratiometric changes
Inverse-pericam YNS T NVY---LEYN G TDQL T G A 5,0 × decrease
G18 SSL E NVY---LEYN G TRDQ E G T 4,3 × increase
GCaMP1 SSL E NVY---LEYN T RDQL E T T 4,3 × increase brighter than G18 due to 145T
GCaMP1.6 SSL E NVY---LEYN T RDQL E T T 4.9 × increase much brighter than GCaMP1
GCaMP2 SSL E NVY---LEYN T RDQL E T T 5 × increase much brighter than GCaMP1.6
Part B: our sensors developed as a result of 145/148 positions mutagenesis
cps1 SSL N NVY---LEYN T RDQL N T F Low increase
cps1(A) SSL N NVY---LEYN A RDQL N A F 1,4 × decrease
cps1(S) SSL N NVY---LEYN S RDQL N S F 1,5 × increase
cps2 SSL E NVY---LEYN T RDQL E T F 14,5 × increase
cps2(A) SSL E NVY---LEYN A RDQL E A F no response
cps2(S) SSL E NVY---LEYN S RDQL E S F 14,5 × increase
cps4 SSL D NVY---LEYN T RDQL D T F low increase
cps4(S) SSL D NVY---LEYN A RDQL D A F 7,2 × ratiometric changes
cps4(A) SSL D NVY---LEYN S RDQL D S F 8,0 × ratiometric changes
Part C: Sensors developed after cpS2 random mutagenesis
Case12 SSL E NVY---LEYN T RDQL E T F 12.0 × increase fast maturation
Case16 SSL E NVY---LEYN S RDQL E S F 16.5 × increase