Related Experiment Video

Updated: Aug 4, 2026

Identification and Analysis of Mouse Erythroid Progenitors using the CD71/TER119 Flow-cytometric Assay
15:32

Identification and Analysis of Mouse Erythroid Progenitors using the CD71/TER119 Flow-cytometric Assay

Published on: August 5, 2011

Regulation of protein 4.1R, p55, and glycophorin C ternary complex in human erythrocyte membrane

W Nunomura1, Y Takakuwa, M Parra

  • 1Department of Biochemistry, School of Medicine, Tokyo Women's Medical University, Shinjuku, Tokyo 162-8666, Japan.

The Journal of Biological Chemistry
|June 1, 2000
PubMed

Insights

Protein 4.1R regulates the erythrocyte membrane

Area of Science:

  • Biochemistry
  • Cell Biology
  • Membrane Protein Interactions

Background:

  • The erythrocyte membrane relies on protein complexes for structural integrity.
  • The glycophorin C (GPC)-4.1R-p55 complex is crucial, but its regulation is poorly understood.

Purpose of the Study:

  • To elucidate the molecular mechanisms underlying the GPC-4.1R-p55 complex formation.
  • To investigate the regulatory role of protein 4.1R in this complex.

Main Methods:

  • Protein binding assays to identify interaction interfaces.
  • Affinity measurements to quantify binding strengths.
  • Calcium-dependent calmodulin binding studies.

Main Results:

  • Identified specific 4.1R domains (exon 8 and 10) as binding sites for GPC and p55.
  • Demonstrated that 4.1R significantly enhances p55 binding to GPC.
  • Showed that calmodulin binding to 4.1R modulates its interactions with GPC and p55 in a calcium-dependent manner.

Conclusions:

  • Protein 4.1R plays a key regulatory role in the GPC-4.1R-p55 ternary complex.
  • The complex's stability is dynamically regulated by calmodulin and calcium ions.

More Related Videos

Characterization of Glycoproteins with the Immunoglobulin Fold by X-Ray Crystallography and Biophysical Techniques08:58

Characterization of Glycoproteins with the Immunoglobulin Fold by X-Ray Crystallography and Biophysical Techniques

Published on: July 5, 2018

Measuring Erythrocyte Complement Receptor 1 Using Flow Cytometry07:20

Measuring Erythrocyte Complement Receptor 1 Using Flow Cytometry

Published on: May 19, 2020

Related Concept Videos

GTPases and their Regulation02:14

GTPases and their Regulation

Guanine nucleotide-binding proteins (G-proteins), also known as GTPases, are a superfamily of proteins that regulate many cellular processes, such as cell signaling, vesicular transport, and the regulation of cell shape and motility. Mutation or dysfunction of these proteins can lead to disease. There are around 40,000 known G-proteins that can broadly be classified into two groups ‒  small G-proteins consisting of a single domain and large multi-domain G-proteins.
Large G-proteins, also known...
Covalently Linked Protein Regulators02:04

Covalently Linked Protein Regulators

Proteins can undergo many types of post-translational modifications, often in response to changes in their environment. These modifications play an important role in the function and stability of these proteins. Covalently linked molecules include functional groups, such as methyl, acetyl, and phosphate groups, and also small proteins, such as ubiquitin. There are around 200 different types of covalent regulators that have been identified.
These groups modify specific amino acids in a protein.
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...
Rab Proteins01:14

Rab Proteins

Rab proteins constitute the largest family of monomeric GTPases, of which 70 members are present in humans. Rab proteins and their effectors regulate consecutive stages of vesicle transport such as vesicle transport, docking, and fusion to the correct recipient membrane.
Rab proteins switch between a cytosolic, GDP-bound inactive state and a membrane-anchored, GTP-bound active state. By themselves, Rabs show slow rates of GDP/GTP exchange and GTP hydrolysis. Thus, Rab proteins are considered...
Protein Modifications in the RER01:26

Protein Modifications in the RER

Modification of secretory and transmembrane proteins entering the rough ER begins in the ER lumen. These modifications aid in protein folding and stabilize the acquired tertiary structure. Protein modifications in the rough ER co-occur at different stages of protein folding.
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal sequences.
Protein Folding Quality Check in the RER01:29

Protein Folding Quality Check in the RER

ER is the primary site for the maturation and folding of soluble and transmembrane secretory proteins. The calnexin cycle is a specific chaperone system that folds and assesses the confirmation of N-glycosylated proteins before they can exit the ER lumen. The primary players of this quality check pipeline are the lectins, ER-resident chaperones, and a glucosyl transferase enzyme. In case the calnexin system in the lumen fails to salvage a misfolded protein, it is transported to the cytoplasm...