Fig. 2.

Neuronal isoQC expression, subcellular localization and co-expression of CCL2 in mouse brain and primary neurons. a IsoQC was strictly co-localized with the neuronal marker HuC/D in brain sections of 17-month-old wild-type mice demonstrating a neuron-specific expression. Cells which did not display HuC/D immunoreactivity were also negative for isoQC labeling (arrows). b IsoQC was co-localized with cellular compartment markers calreticulin and syntaxin-6, consistent with a subcellular localization in endoplasmic reticulum and Golgi apparatus. c The putative isoQC substrate CCL2 was found to be co-expressed by isoQC-immunoreactive neurons in cortex of wild-type mice (top) and in primary neuronal cultures (bottom). d The conversion of CCL2 by recombinant isoQC was analyzed in a kinetic assay. The progress curve (black trace) was in accordance with a curve modeled according to the integrated form of the Michaelis–Menten equation (red trace), enabling the determination of the kinetic parameters K _M (19.8 ± 0.4 μM) and k _cat (0.76 ± 0.01 s⁻¹)