The C3 3′ UTR is not involved in the coregulation of C3 by C1. A, The chimeric construct Hsp70A/RbcS2pro:Ble-cRluc:C3-3′UTR of pSK27 (Voytsekh et al., 2008) that was used for transformation resulting in transgenic lines cRluc1 and -2 is schematically shown as well as the construct used for C1 overexpression (C1ox; Iliev et al., 2006). ORF, Open reading frame. B, Different amounts of proteins from a crude extract (90, 60, and 30 μg per lane) labeled as 3x, 2x, and 1x, respectively, of cRluc1 and -2 cells that had been transformed in some cases with the C1ox vector (cRluc1::C1ox and cRluc2::C1ox) were separated by SDS-PAGE. They were used for immunodetection with anti-C1 and anti-C3 antibodies, respectively. C, Quantification of the expression levels of C1 and C3 via ImageMaster 2D Elite version 4.01 (GE Healthcare) according to “Materials and Methods” in C1ox strains in percentage in comparison with the appropriate control strain (n = 2). D, Measurements of luciferase activities (cRLUC) in the cRluc1 and -2 strains in comparison with the cRluc1::C1ox and cRluc2::C1ox strains in relative light units (RLU; n = 3). Error bars represent the se of technical replicates. Cells were grown at 23°C and used at LD2 to measure the cRLUC activities.