Figure 6.

Illustration of distinct but similar functions of different synaptotagmins: Syt10 acts as a Ca²⁺ sensor for IGF-1 containing vesicles in mitral neurons from olfactory bulb. (A) IGF-1 secretion from cultured olfactory bulb neurons is stimulated by depolarization with 15 mm KCl, but impaired by deletion of Syt10 (this and the following panels were modified from Cao et al. 2011). (B) Syt10 colocalizes with IGF-1 containing vesicles in the somatodendritic regions of cultured mitral neurons. Images show double immunofluorescence labeling of tagged Syt10 and either IGF-1, synapsin, or MAP2 as indicated. (C) Illustration of the distinct functions of Syt1 and Syt10 as Ca²⁺ sensors exclusively for synaptic and IGF-1-containing vesicles, respectively, in mitral neurons.