3’ rapid amplification of cDNA ends (3’RACE) indicated that this is unlikely. We detected only the full length of this 3’UTR in fresh tissue (Figure 5A, lower band, Figure S6). Surprisingly, we observed two additional larger bands (Figure 5A). Indeed, two novel, longer BK 3’UTRs have recently been cloned (Beisel et al., 2007) in rat inner ear hair cells. We determined that they are expressed in neurons and constructed a schematic summarizing BK α 3’UTR heterogeneity (Figure 5B, S5) using a rat genome database to determine chromosomal position of 3’UTR sequences, and 3’UTR sequence described by us and others (Beisel et al., 2007). The three different 3’UTRs associated with BK α are a result of alternative splicing in the 5’-end of the coding sequence and the 3’UTR region. Despite partial homology of one of the new 3’UTRs (2.2) with the previously known 3’UTR (2.1), only 3’UTR-2.1 has the miR-9 MRE (Figure 5B, C).
