GCaMP variants were made in a modified SIV-based lentiviral construct, pGP-syn-GCaMP-nls-mCherry-WPRE, derived from pCL20cSLFR MSCV-GFP51. The prolentiviral vector included a 476-bp human synapsin promoter, GCaMP, a nuclear localization sequence fused to mCherry, and the woodchuck hepatitis post-transcriptional regulatory element. Site-directed mutagenesis was conducted by PCR and mutated regions were incorporated into the lentiviral constructs by gene assembly52.
