Related Experiment Video
Updated: Jul 17, 2026

Utilizing pHluorin-tagged Receptors to Monitor Subcellular Localization and Trafficking
Published on: March 16, 2017
PF-4/CXCL4 and CXCL4L1 exhibit distinct subcellular localization and a differentially regulated mechanism of
Laura Lasagni1, Renaud Grepin, Benedetta Mazzinghi
1Excellence Center for Research, Transfer and High Education De Novo Therapies, University of Florence, Florence, Italy.
Abstract:
PF-4/CXCL4 is a member of the CXC chemokine family, which is mainly produced by platelets and known for its pleiotropic biological functions. Recently, the proteic product of a nonallelic variant gene of CXCL4 was isolated from human platelets and named as CXCL4L1. CXCL4L1 shows only 4.3% amino acid divergence in the mature protein, but exhibits a 38% amino acid divergence in the signal peptide region. We hypothesized that this may imply a difference in the cell type in which CXCL4L1 is expressed or a difference in its mode of secretion. In different types of transfected cells, CXCL4 and CXCL4L1 exhibited a distinct subcellular localization and a differential regulation of secretion, CXCL4 being stored in secretory granules and released in response to protein kinase C activation, whereas CXCL4L1 was continuously synthesized and secreted through a constitutive pathway. A protein kinase C-regulated CXCL4 secretion was observed also in lymphocytes, a cell type expressing mainly CXCL4 mRNA, whereas smooth muscle cells, which preferentially expressed CXCL4L1, exhibited a constitutive pathway of secretion. These results demonstrate that CXCL4 and CXCL4L1 exhibit a distinct subcellular localization and are secreted in a differentially regulated manner, suggesting distinct roles in inflammatory or homeostatic processes.
Related Concept Videos
Overview of Secretory Vesicles
Various proteins regulate the aggregation of molecules inside the secretory vesicles. Chromogranins...
Vesicular Tubular Clusters
With the help of motor proteins such...
Role of ER in the Secretory Pathway
Components of the secretory pathway
About a third of proteins synthesized in the cell are sorted via the secretory route. They shuffle between different compartments in membrane-bound vesicles until they reach their final destination. The main intracellular compartments involved...
Regulation of Nuclear Protein Sorting
Clathrin Coated Vesicles
COP Coated Vesicles

