Related Experiment Video

Updated: Aug 8, 2026

In situ Subcellular Fractionation of Adherent and Non-adherent Mammalian Cells
09:20

In situ Subcellular Fractionation of Adherent and Non-adherent Mammalian Cells

Published on: July 24, 2010

Association of p60c-src with endosomal membranes in mammalian fibroblasts

K B Kaplan1, J R Swedlow, H E Varmus

  • 1Department of Microbiology, University of California, San Francisco 94143.

The Journal of Cell Biology
|July 1, 1992
PubMed

Insights

The protein p60c-src localizes to endosomes in mammalian fibroblasts, not plasma membranes. This finding suggests a role for p60c-src in regulating endosomal membranes and protein trafficking.

Area of Science:

  • Cell Biology
  • Molecular Biology
  • Biochemistry

Background:

  • The protein p60c-src is involved in various cellular processes.
  • Its precise subcellular localization is crucial for understanding its function.
  • Previous studies have suggested roles in signaling pathways, but localization details were unclear.

Purpose of the Study:

  • To determine the subcellular localization of p60c-src in mammalian fibroblasts.
  • To investigate the association of p60c-src with specific cellular organelles.
  • To elucidate the functional implications of p60c-src localization in membrane trafficking.

Main Methods:

  • Indirect immunofluorescence microscopy with three-dimensional optical sectioning.
  • Co-localization studies using antibodies against specific membrane markers, including the cation-dependent mannose-6-phosphate receptor (CI-MPR).
  • Biochemical fractionation of cellular membranes and density shift experiments.

Main Results:

  • p60c-src exhibits granular cytoplasmic staining co-localizing with the microtubule organizing center.
  • Significant co-localization of p60c-src with CI-MPR, an endosomal marker, was observed.
  • p60c-src and CI-MPR cluster at spindle poles during mitosis and peri-centriolar regions upon brefeldin A treatment.
  • Biochemical fractionation indicates p60c-src is primarily associated with endocytic membranes, not plasma membranes.

Conclusions:

  • The majority of membrane-associated p60c-src resides on endosomes.
  • These findings support a role for p60c-src in the regulation of endosomal membranes.
  • p60c-src may be involved in protein trafficking processes mediated by endosomes.

More Related Videos

The Cell-based L-Glutathione Protection Assays to Study Endocytosis and Recycling of Plasma Membrane Proteins09:22

The Cell-based L-Glutathione Protection Assays to Study Endocytosis and Recycling of Plasma Membrane Proteins

Published on: December 13, 2013

In Vitro Polymerization of F-actin on Early Endosomes12:15

In Vitro Polymerization of F-actin on Early Endosomes

Published on: August 28, 2017

Related Concept Videos

The Early Endosome: Endocytosis of Transferrin01:28

The Early Endosome: Endocytosis of Transferrin

Essential proteins such as insulin or low-density lipoprotein (LDL) and micronutrients such as iron enter a eukaryotic cell through receptor-mediated endocytosis. Subsequently, the early endosomes fuse with the vesicles containing such receptor-ligand complexes and play a vital role in sorting the incoming ligands and receptors. While the ligands are either degraded inside the vesicle or released into the cytosol, their receptors are returned to the plasma membrane for further rounds of...
Intralumenal Vesicles and Multivesicular Bodies01:38

Intralumenal Vesicles and Multivesicular Bodies

Intraluminal vesicles (ILVs) are small vesicles 50-80 nm in diameter formed during the maturation of early endosomes. A specialized endosome containing numerous ILVs is called a multivesicular body (MVB). ILVs contain internalized molecules such as antigens, nucleic acids, proteins, and metabolites. Some of these molecules are released from the MVBs inside exosomes and are transported to other cells. Other MVBs contain molecules that are retained in the ILVs and are later degraded within the...
Regulation of Nuclear Protein Sorting01:45

Regulation of Nuclear Protein Sorting

Nuclear protein sorting regulates nucleus composition and gene expression, crucial for determining the fate of a eukaryotic cell. Hence, the entry and exit of molecules across the nuclear envelope is a tightly controlled process. Nuclear protein sorting can be inhibited by one of the following ways: 1) masking cargo signal sequences, 2) modifying the nuclear receptor's affinity for cargo, 3) controlling the nuclear pore size, 4) retaining the cargo during its transit to the cytosol or the...
Coat Assembly and GTPases01:33

Coat Assembly and GTPases

Vesicles incorporate different coat protein subunits in different cell locations, which changes the properties of the coat, such as the shape and geometry of the transport vesicles. Thus, vesicle coat proteins also play a significant role in cargo selection.
Coat assembly depends on the local availability of phosphatidylinositol phosphates or PIPs and GTP-binding proteins. Adaptor proteins, which link the coat proteins to the membrane, bind to these PIPs and play a crucial role in controlling...
ER Retrieval Pathway01:45

ER Retrieval Pathway

In the secretory pathway, vesicles transport proteins from one cellular compartment to another in forward transport to deliver the protein to its correct location. Occasionally, misfolded proteins and incorrect proteins escape their original compartments, and a retrieval pathway is used to return the escaped proteins to their original compartment.
The ER uses many checkpoints to prevent the entry of incorrectly folded or a resident protein as cargo onto a transport vesicle. These mechanisms...
Receptor Downregulation in MVBs01:15

Receptor Downregulation in MVBs

Multivesicular bodies (MVBs) are mature endosomes that sort ubiquitinated proteins and then fuse with lysosomes to degrade the sorted proteins. Epidermal growth factor (EGF) and its receptor (EGFR) form a complex that can be internalized through endocytosis, sorted into an MVB, and later degraded.
The EGFR can initiate signaling pathways that  lead to cell proliferation, migration, and differentiation. Overexpression of EGFR  stimulates cells to proliferate. Excessive  EGFR activation may...