A. Line drawing showing location of the MH box sequences, transcription factor binding sites and the position of the 1,726bp deletion created within the construct. SS encodes the signal sequence, and exon 1 encodes the first SCR domain of the CR1 protein. B. Line drawing showing the location of oligonucleotide probes for PCR analysis of WT and Cr2iΔ animals. After passage through sperm, the pACN cassette is removed leaving only a single Lox site within the Cr2 gene. All figures not drawn to scale. C. PCR analysis of genomic DNA from wildtype (WT/C57BL/6), heterozygote (HET) and knockout (KO) mice. DNA fragments were resolved on a 6% polyacrylamide gel. Locations for the oligonucleotides used in this assay are shown in Panel B.