Question

provide the function, cellular location and general structural features that allows the protein to perform its function.

protein name is: 1GAG -the crystal structure of tyrosine receptor kinase with a Bisubstrate Inhibitor

Answer 1

Tyrosine receptor kinase: A tyrosine kinase is an enzyme that can transfer a phosphate group from ATP to a protein in a cell. It functions as an "on" or "off" switch in many cellular functions. Tyrosine kinases are a subclass of protein kinase.

The phosphate group is attached to the amino acid tyrosine on the protein. Tyrosine kinases are a subgroup of the larger class of protein kinases that attach phosphate groups to other amino acids (serine and threonine). Phosphorylation of proteins by kinases is an important mechanism in communicating signals within a cell (signal transduction) and regulating cellular activity, such as cell division.

Protein kinases can become mutated, stuck in the "on" position, and cause unregulated growth of the cell, which is a necessary step for the development of cancer. Therefore, kinase inhibitors, such as imatinib, are often effective cancer treatments.

Most tyrosine kinases have an associated protein tyrosine phosphatase, which removes the phosphate group.

Cellular Location : Most of these tumors are found in the stomach, though they can also be located in the small intestine or elsewhere in the intestinal tract. The cells of these tumors have a growth factor receptor associated with tyrosine kinase activity.

Structure: Included in a number of the structural features that can be recognized in all protein tyrosine kinases are an ATP binding site, three residues that are thought to be associated with the function of the third phosphate group (often called the gamma-phosphate group) of an ATP molecule bound to the enzyme, and a possible catalytic site of the enzyme that is an amino acid. Also very common among protein tyrosine kinases are two peptide sequences.

Function : Kinase is a large family of enzymes that are responsible for catalyzing the transfer of a phosphoryl group from a nucleoside triphosphate donor, such as ATP, to an acceptor molecule.Tyrosine kinases catalyze the phosphorylation of tyrosine residues in proteins The phosphorylation of tyrosine residues in turn causes a change in the function of the protein that they are contained in.

Phosphorylation at tyrosine residues controls a wide range of properties in proteins such as enzyme activity, subcellular localization, and interaction between molecules. Furthermore, tyrosine kinases function in many signal transduction cascades wherein extracellular signals are transmitted through the cell membrane to the cytoplasm and often to the nucleus, where gene expression may be modified.Finally mutations can cause some tyrosine kinases to become constitutively active, a nonstop functional state that may contribute to initiation or progression of cancer.

Bisubstrate inhibitors consist of two conjugated fragments, each targeted to a different binding site of a bisubstrate enzyme. The design of bisubstrate inhibitors presupposes the formation of the ternary complex in the course of the catalyzed reaction.

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