Insertional mutation in CD98hc. A. Schematic representation of the mutation in CD98hc. Nine exons are shown as boxes with untranslated regions at 5' and 3' ends. The gene trap vector was inserted within the translated region of exon 9 (arrow) to yield an in-frame fusion transcript with β-geo. Binding sites for oligonucleotide primer sets A (black arrowheads) and B (white arrowheads) used for PCR genotyping are indicated. CD98hc is a ~80 kD membrane protein, which is composed of N-terminal cytoplasmic, transmembrane (TM), and C-terminal extracellular domains. The mutant allele is expected to produce a ~220 kD protein whose C-terminal 102 amino acids are replaced with β-geo. B. Representative results of genotyping PCR of 3-week-old offspring from a heterozygous (CD98hcΔ/+) intercross. Primer set A, which amplifies whole translated region of exon 9 (496 bp), yields the expected PCR product from wild type CD98hc allele (+). Primer set B, which amplifies a part of β-geo sequence (681 bp), yields PCR products only from the mutant allele (Δ). Note that primer set A yields the 496-bp band that shows the presence of wild type CD98hc allele in all the offspring. Note, the amount of genomic DNA used for each PCR was not quantified, and therefore quantitative levels cannot be directly compared.