Fig 1: Expression of Munc13 isoforms in the mouse adrenal gland.KO mouse lines of the respective Munc13 isoform were used as control. The antibodies used to detect individual Munc13 isoforms and loading controls are indicated on the left. (A) Munc13-1 (*) is barely detectable in perinatal adrenal gland. (B) ubMunc13-2, but not bMunc13-2, is expressed. (C) Munc13-3 was not detected. (D) Baiap3 was detected, but not (E) Munc13-4. Jx refers to mice homozygous for the Unc13dJinxmutation (Crozat et al., 2007). (F) Munc13-1 and Baiap3 are mainly located in the medulla (Med), but ubMunc13-2 is present in cortex (Cort) as well. Please note that the difference in the position of ubMunc13-2 relative to the marker in panels (B) and (F) is due to how far the respective gels were run. Loading controls were valosin-containing protein (VCP), glyceraldehyde-3-phosphate dehydrogenase (GAPDH) and CgA. Brain samples, and spleen tissue in the case of Munc13-4, were used for comparison. Please note that the Baiap3KO (Wojcik et al., 2013) and Unc13aKO animals express truncated protein products, whereas the truncated product present in the Unc13bKO (Cooper et al., 2012) is not shown here. Based on previous analyses of the Unc13aKO and Unc13bKO mice (Augustin et al., 1999; Cooper et al., 2012; Varoqueaux et al., 2002), the truncated Munc13-1 and Munc13-2 products are neither functional, nor do they have a dominant-negative effect. The truncated Baiap3 product was not detected in adrenal gland, and its effect in the brain, where it can be detected in young animals up to P21, is currently unknown (Wojcik et al., 2013). See also Figure 1—figure supplement 1.DOI: http://dx.doi.org/10.7554/eLife.10635.003