Which one of the following signaling molecules is NOT a protein or a peptide?
Epinephrine
Signaling Molecules Overview
Signaling molecules are essential for communication between cells and within cells. They trigger specific responses in target cells by binding to receptors. These molecules can belong to various chemical classes, including proteins, peptides, amino acid derivatives, steroids, lipids, and gases.
Analyzing Signaling Molecule Options
Let's examine the chemical nature of each signaling molecule listed in the options:
- Transforming growth factor α (TGF-α): This is a type of growth factor. Growth factors are typically proteins or small peptides that stimulate cell growth, proliferation, differentiation, or survival. TGF-α is known to be a protein.
- Erythropoietin: This is a hormone produced by the kidney. It is a glycoprotein, which means it is a protein molecule with attached carbohydrate chains. Glycoproteins are a type of protein.
- Granulocyte colony stimulating factor: Often abbreviated as G-CSF, this is another type of colony-stimulating factor. These factors are glycoproteins that regulate blood cell production. G-CSF is a protein that stimulates the production of granulocytes.
- Epinephrine: Also known as adrenaline, epinephrine is a hormone and neurotransmitter. Chemically, it is classified as a catecholamine. Catecholamines are organic compounds derived from the amino acid tyrosine and are not proteins or peptides.
Identifying Non-Protein/Peptide Molecule
Based on the analysis of the chemical nature of each signaling molecule:
- TGF-α is a protein.
- Erythropoietin is a glycoprotein (a type of protein).
- Granulocyte colony stimulating factor is a glycoprotein (a type of protein).
- Epinephrine is a catecholamine, derived from an amino acid, but it is not a protein or a peptide chain.
Therefore, epinephrine is the signaling molecule among the given options that is NOT a protein or a peptide.
Important Questions from Cell signaling
In the table below Column A lists ligands and Column B lists classes of receptors
Column A Column B A Serotonin i Binding activates a G-protein which activates or inhibits an enzyme that generates a specific second messenger and opens ion channel B Interferons ii Binding causes receptor monomers to dimerize. Dimeric receptor then interacts with and activates one or more cytosolic tyrosine protein kinases C Glycine iii Binding changes the conformation of the receptor so that specific ions flow through it D Insulin iv Binding leads to activation of intrinsic tyrosine kinase activity Which one is the correct match?
Receptor for which one of the following proteins spans the plasma membrane of target cells but DOES NOT contain intrinsic protein kinase activity?
Which one of the following amino acids is characteristic of and is conserved in response regulator of plant two-component systems?
Receptor tyrosine kinases (RTKs) form a large and important class of cell surface receptors whose ligands are soluble or membrane bound protein or peptide hormones. Which of the following statement is INCORRECT?
Nitric oxide (NO) acts as intracellular second messenger by stimulating
