Amino Acid Builder

Which of the following amino acids is classified as a basic amino acid?

In the context of protein structure, which amino acid often forms disulfide bonds, contributing to the tertiary structure of proteins?

A researcher is studying a protein known for its role in signal transduction. Analysis shows that this protein has a high proportion of tyrosine. Considering the function and structure of tyrosine, what post-translational modification is this protein likely to undergo to facilitate its role in signal transduction?

Enzyme X is crucial for a metabolic pathway in the liver. It is known that Enzyme X has a high affinity for a specific amino acid, which acts as an allosteric regulator. This amino acid is unique in having a thiol group in its side chain, which is key to its regulatory function in this pathway. 

Which of the following amino acids acts at the allosteric regulator site described in the excerpt?

In a study of protein folding, researchers found that a particular protein loses its functionality at high temperatures. This protein is rich in glutamic acid and histidine. It was observed that at a pH or around 5, the protein maintained its function better at elevated temperatures.

What property of glutamic acid and histidine most likely contributes to the protein’s increased stability at this pH?

Passage 1

Researchers are investigating the structural properties of G-protein coupled receptors (GPCRs), particularly focusing on the epidermal growth factor receptor (EGFR). These receptors are known for their significant role in cell signaling pathways, often mediating critical cellular processes like growth and differentiation. The EGFR, a transmembrane protein, consists of an extracellular ligand-binding domain, a single hydrophobic transmembrane helix, and an intracellular tyrosine kinase domain. The intracellular domain is activated upon the binding of EGF, an anionic protein, to the extracellular domain, triggering a cascade of downstream signaling events.

In a parallel study, the voltage-gated sodium channels (Nav1.5) are being examined. These channels, crucial for the initiation and propagation of action potentials in neurons, are composed of a pore-forming α-subunit and two β-subunits. The α-subunit has four homologous domains (I-IV), each with six transmembrane segments (S1-S6). The S4 segment is known for its voltage-sensing capabilities due to the presence of positively charged amino acids at every third position.

Based on the passage, which amino acid is most likely found in the S1 segment?

Passage 1

Researchers are investigating the structural properties of G-protein coupled receptors (GPCRs), particularly focusing on the epidermal growth factor receptor (EGFR). These receptors are known for their significant role in cell signaling pathways, often mediating critical cellular processes like growth and differentiation. The EGFR, a transmembrane protein, consists of an extracellular ligand-binding domain, a single hydrophobic transmembrane helix, and an intracellular tyrosine kinase domain. The intracellular domain is activated upon the binding of EGF, an anionic protein, to the extracellular domain, triggering a cascade of downstream signaling events.

In a parallel study, the voltage-gated sodium channels (Nav1.5) are being examined. These channels, crucial for the initiation and propagation of action potentials in neurons, are composed of a pore-forming α-subunit and two β-subunits. The α-subunit has four homologous domains (I-IV), each with six transmembrane segments (S1-S6). The S4 segment is known for its voltage-sensing capabilities due to the presence of positively charged amino acids at every third position.

Given the role of the S4 segment in Nav1.5 as a voltage sensor, which characteristic of the amino acids in this segment is most critical for its function?

Passage 1

Researchers are investigating the structural properties of G-protein coupled receptors (GPCRs), particularly focusing on the epidermal growth factor receptor (EGFR). These receptors are known for their significant role in cell signaling pathways, often mediating critical cellular processes like growth and differentiation. The EGFR, a transmembrane protein, consists of an extracellular ligand-binding domain, a single hydrophobic transmembrane helix, and an intracellular tyrosine kinase domain. The intracellular domain is activated upon the binding of EGF, an anionic protein, to the extracellular domain, triggering a cascade of downstream signaling events.

In a parallel study, the voltage-gated sodium channels (Nav1.5) are being examined. These channels, crucial for the initiation and propagation of action potentials in neurons, are composed of a pore-forming α-subunit and two β-subunits. The α-subunit has four homologous domains (I-IV), each with six transmembrane segments (S1-S6). The S4 segment is known for its voltage-sensing capabilities due to the presence of positively charged amino acids at every third position.

The passage mentions that the EGFR has an extracellular ligand-binding domain. Which type of amino acid would you most likely find in abundance in this domain, and why?

Passage 1

Researchers are investigating the structural properties of G-protein coupled receptors (GPCRs), particularly focusing on the epidermal growth factor receptor (EGFR). These receptors are known for their significant role in cell signaling pathways, often mediating critical cellular processes like growth and differentiation. The EGFR, a transmembrane protein, consists of an extracellular ligand-binding domain, a single hydrophobic transmembrane helix, and an intracellular tyrosine kinase domain. The intracellular domain is activated upon the binding of EGF, an anionic protein, to the extracellular domain, triggering a cascade of downstream signaling events.

In a parallel study, the voltage-gated sodium channels (Nav1.5) are being examined. These channels, crucial for the initiation and propagation of action potentials in neurons, are composed of a pore-forming α-subunit and two β-subunits. The α-subunit has four homologous domains (I-IV), each with six transmembrane segments (S1-S6). The S4 segment is known for its voltage-sensing capabilities due to the presence of positively charged amino acids at every third position.

Considering the structural properties of GPCRs and the voltage-gated sodium channels, what is the significance of the distribution and type of amino acids in the transmembrane helix of these proteins?