Positioning these proteins at the site of the developing exosporium (57, 58, 65?7). No such localization domain is present in the BxpB sequence. Therefore, my colleagues and I have proposed a model whereby BxpB is delivered to the spore by virtue of forming a complex with BclA and possibly, to a lesser extent, with other exosporium-targeting motif sequences (58). In keeping with this, we observed