second messenger

Examples of second messenger in the following topics:

• Plasma Membrane Hormone Receptors

  • The hormone that initiates the signaling pathway is called a first messenger, which activates a second messenger in the cytoplasm.
  • One very important second messenger is cyclic adenosine monophosphate (cAMP).
  • Hormone binding to receptor activates a G protein, which in turn activates adenylyl cyclase, converting ATP to cAMP. cAMP is a second messenger that mediates a cell-specific response.

• Methods of Intracellular Signaling

  • The activation of second messengers is also a common event after the induction of a signaling pathway.
  • Calcium ion is a widely-used second messenger.
  • Another second messenger utilized in many different cell types is cyclic AMP (cAMP).
  • Present in small concentrations in the plasma membrane, inositol phospholipids are lipids that can also be converted into second messengers.
  • This diagram shows the mechanism for the formation of cyclic AMP (cAMP). cAMP serves as a second messenger to activate or inactivate proteins within the cell.

• Cell Signaling and Cellular Metabolism

  • When energy is needed, glycogen is quickly reconverted to glucose. ) Phosphorylation of the second enzyme, glycogen synthase (GS), inhibits its ability to form glycogen from glucose.
  • This diagram shows the mechanism for the formation of cyclic AMP (cAMP). cAMP serves as a second messenger to activate or inactivate proteins within the cell.

• Binding Initiates a Signaling Pathway

  • In a signaling pathway, second messengers, enzymes, and activated proteins interact with specific proteins, which are in turn activated in a chain reaction that eventually leads to a change in the cell's environment.

• DNA and RNA

  • This intermediary is the messenger RNA (mRNA).
  • The difference between the sugars is the presence of the hydroxyl group on the second carbon of the ribose and hydrogen on the second carbon of the deoxyribose.

• RNA Splicing

  • Alternative splicing can occur due to the different ways in which an exon can be excluded from or included in the messenger RNA.
  • The pattern of splicing and production of alternatively-spliced messenger RNA is controlled by the binding of regulatory proteins (trans-acting proteins that contain the genes) to cis-acting sites that are found on the pre-RNA.
  • Proteins that are translated from alternatively-spliced messenger RNAs differ in the sequence of their amino acids which results in altered function of the protein.
  • The splicing of messenger RNA is accomplished and catalyzed by a macro-molecule complex known as the spliceosome.
  • Equally as important are the silencers and enhancers that are found on the messenger RNAs, also known as cis-acting sites.

• How Hormones Work

  • Hormones are chemical messengers that relay messages to cells that display specific receptors for each hormone and respond to the signal.
  • In essence, it is a chemical messenger that transports a signal from one cell to another.

• Pathogen Recognition

  • A cytokine is a chemical messenger that regulates cell differentiation (form and function), proliferation (production), and gene expression to affect immune responses.
  • A second class of cytokines is interferons , which are released by infected cells as a warning to nearby uninfected cells.

• The Central Dogma: DNA Encodes RNA and RNA Encodes Protein

  • The central dogma of molecular biology describes the flow of genetic information in cells from DNA to messenger RNA (mRNA) to protein.
  • If the transcribed gene encodes a protein, the result of transcription is messenger RNA (mRNA), which will then be used to create that protein in the process of translation.
  • Instructions on DNA are transcribed onto messenger RNA.
  • Ribosomes are able to read the genetic information inscribed on a strand of messenger RNA and use this information to string amino acids together into a protein.

• Types of RNA

  • This intermediary is the messenger RNA (mRNA).
  • The ribosome acts like a giant clamp, holding all of the players in position, and facilitating both the pairing of bases between the messenger and transfer RNAs, and the chemical bonding between the amino acids.
  • These subunits do not carry instructions for making a specific proteins (i.e., they are not messenger RNAs) but instead are an integral part of the ribosome machinery that is used to make proteins from mRNAs.