The Diffusion Model of Intra-Golgi Transport Has Limited Power

Abstract

The Golgi complex (GC) is the main station along the cell biosecretory pathway. Until now, mechanisms of intra-Golgi transport (IGT) have remained unclear. Herein, we confirm that the goodness-of-fit of the regression lines describing the exit of a cargo from the Golgi zone (GZ) corresponds to an exponential decay. When the GC was empty before the re-initiation of the intra-Golgi transport, this parameter of the curves describing the kinetics of different cargoes (which are deleted in Golgi vesicles) with different diffusional mobilities within the GZ as well as their exit from the GZ was maximal for the piecewise nonlinear regression, wherein the first segment was horizontal, while the second segment was similar to the exponential decay. The kinetic curve describing cargo exit from the GC per se resembled a linear decay. The Monte-Carlo simulation revealed that such curves reflect the role of microtubule growth in cells with a central GC or the random hovering of ministacks in cells lacking a microtubule. The synchronization of cargo exit from the GC already filled with a cargo using the wave synchronization protocol did not reveal the equilibration of cargo within a Golgi stack, which would be expected from the diffusion model (DM) of IGT. Moreover, not all cisternae are connected to each other in mini-stacks that are transporting membrane proteins. Finally, the kinetics of post-Golgi carriers and the important role of SNAREs for IGT at different level of IGT also argue against the DM of IGT.

Mechanisms of Formation of Antibodies against Blood Group Antigens That Do Not Exist in the Body

“…The Golgi glycosylation enzymes are present in the Golgi cisternal membranes and are localized in accordance with the consequences of the glycosylation process. The transport through the GC is based on the "kiss and run" transport model [39][40][41][42][43][44][45]. Several Golgi enzymes are involved in the production of AgA and AgB.…”

The Regulated Secretion and Models of Intracellular Transport: The Goblet Cell as an Example

“…To make such a system work: (1) compartments with different ionic environments should be narrowly connected to limit mixing and (2) the concentration of various RS proteins along these interconnected, but different, compartment domains should create a diffusion gradient along tubular compounds [83,85,86]. It seems that the KARM can explain the biogenesis and maturation of immature SGs [2,91,92]. However, the number of rims capable of serving as a mechanism for the progression of cargo domains is low, and there is no stretching within the edges of the first and second Golgi cisternae.…”

Understanding the Golgi Apparatus and Intracellular Transport Pathways

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“…The same mechanism may be responsible for the fission of intercisternal connections. COPI is involved in the formation of cisternal pores [1,2,8].…”