While so-called Golgi-resident proteins like galactosyltransferase show highest dwell times within the Golgi complex, they are in fact known to cycle within the early secretory pathway between ER and Golgi compartments [30], [31]. Microtubule depolymerization by nocodazole disrupts such cycling and induces the formation of multiple satellite Golgi stacks in close proximity to ER exit sites [30]. Figure 2B illustrates that in HeLa cells heterologously expressed CNIH-2 behaves like galactosyltransferase as it co-distributes into satellite Golgi stacks upon nocodazole treatment (10 µM, 4 hrs). Thus, exogenously expressed CNIH-2 localizes predominantly to the Golgi complex and behaves similar to other Golgi-resident proteins that cycle continuously between ER and Golgi complex.
