Figure 2.

NBCn1-Exon 7 amplified from human tissues. A. Nested primers designed from the human genome upstream of the MERF initiation site were used in PCR amplification of cDNA from skeletal muscle (lane 2) and kidney (lane 4) libraries. Products were separated on a 1% agarose gel. The products are ~3.7 kbp, as judged by comparison with the 1-kb ladder (lane 1). After sequencing, the bands were identified as genes encoding NBCn1 containing Exon 7. The isolated kidney clone is identical to that of the NBC3 clone reported by the Kurtz group ⁶,¹⁸, except for various point mutations and polymorphisms. No clones were amplified from liver (lane 3) with these particular primers. B. Examples of NBCn1 clones with a MEAD initiation site are shown as amplified in skeletal muscle. Two bands (~3.4 kbp and ~3.7 kbp; lane 2) encoding NBCn1 were observed, as judged by comparison with the 2-log DNA marker (lane 1). The upper band encodes for NBCn1 with Exon 7, and the lower is without Exon 7. Similarly, an NBCn1-Exon 7 clone was amplified from liver (lane 4), and detected by internal gene-specific primers corresponding to an expected ~2.8-kbp product. C. A summary of the tissue distribution found for the Nt of NBCn1 clones (with and without Exon 7) is shown in all experiments. There appears to be a complementary distribution of expression between Nt-Exon 7 clones that begin with MEAD versus MERF. Large (easily detectable) and small (barely detectable) "+" signs indicate relative amplification intensity of signals using our primers.