Figure 1.

Identification of new connexin43 5′-UTRs in mouse. (A) RT–PCR of total RNA prepared from various mouse tissues including heart (H), uterus (U), brain (B), mammary gland (MG), liver (Li) and lung (Lu). A common antisense primer annealing to the cx43 coding region and variable forward primers specific to each of the new exons (see Materials and Methods) were used. The PCR products were analyzed in a 2% agarose gel and visualized by ethidium bromide staining. Subcloning and sequencing of the bands confirmed that the products contain the cx43 UTR1A, 1A_L, 1A_S, 1B_L, 1B_S-1D, 1B_S, 1C-1D, 1C and 1A-1E sequences, as indicated on the right-hand side of the panels. n.s. indicates a non-specific PCR product. On the left-hand side, the positions of the molecular weight markers (PCR markers; Promega) are indicated. (B) Diagram showing the genomic organization of the new cx43 exons, and the splicing combinations found in mouse cx43 mRNAs. Exon1A_S and exon1A partially overlap (11 nt). Asterisk indicates exon1A_L splices directly to exon2. (C) Diagram showing the structure of the transcripts originated from the mouse cx43 gene.