Modelling of the ABL and ARG proteins predicts two functionally critical regions that are natively unfolded

Non-Receptor Tyrosine Kinases: Their Structure and Mechanistic Role in Tumor Progression and Resistance

Protein tyrosine kinases (PTKs) function as key molecules in the signaling pathways in addition to their impact as a therapeutic target for the treatment of many human diseases, including cancer. PTKs are characterized by their ability to phosphorylate serine, threonine, or tyrosine residues and can thereby rapidly and reversibly alter the function of their protein substrates in the form of significant changes in protein confirmation and affinity for their interaction with protein partners to drive cellular functions under normal and pathological conditions. PTKs are classified into two groups: one of which represents tyrosine kinases, while the other one includes the members of the serine/threonine kinases. The group of tyrosine kinases is subdivided into subgroups: one of them includes the member of receptor tyrosine kinases (RTKs), while the other subgroup includes the member of non-receptor tyrosine kinases (NRTKs). Both these kinase groups function as an "on" or "off" switch in many cellular functions. NRTKs are enzymes which are overexpressed and activated in many cancer types and regulate variable cellular functions in response to extracellular signaling-dependent mechanisms. NRTK-mediated different cellular functions are regulated by kinase-dependent and kinase-independent mechanisms either in the cytoplasm or in the nucleus. Thus, targeting NRTKs is of great interest to improve the treatment strategy of different tumor types. This review deals with the structure and mechanistic role of NRTKs in tumor progression and resistance and their importance as therapeutic targets in tumor therapy.

Computational and Biological Investigations on Abl1 Tyrosine Kinase: A Review

Abl1 tyrosine kinase is a validated target for the treatment of chronic myeloid leukemia. It is a form of cancer that is difficult to treat and much research is being done to identify new molecular entities and to tackle drug resistance issues. In recent years, drug resistance of Abl1 tyrosine kinase has become a major healthcare concern. Second and third-generation TKI reported better responses against the resistant forms; still they had no impact on long-term survival prolongation. New compounds derived from natural products and organic small molecule inhibitors can lay the foundation for better clinical therapies in the future. Computational methods, experimental and biological studies can help us understand the mechanism of drug resistance and identify novel molecule inhibitors. ADMET parameters analysis of reported drugs and novel small molecule inhibitors can also provide valuable insights. In this review, available therapies, point mutations, structure-activity relationship and ADMET parameters of reported series of Abl1 tyrosine kinase inhibitors and drugs are summarised. We summarise in detail recent computational and molecular biology studies that focus on designing drug molecules, investigation of natural product compounds and organic new chemical entities. Current ongoing research suggests that selective targeting of Abl1 tyrosine kinase at the molecular level to combat drug resistance in chronic myeloid leukemia is promising.

Order, Disorder, and Everything in Between

In addition to the “traditional” proteins characterized by the unique crystal-like structures needed for unique functions, it is increasingly recognized that many proteins or protein regions (collectively known as intrinsically disordered proteins (IDPs) and intrinsically disordered protein regions (IDPRs)), being biologically active, do not have a specific 3D-structure in their unbound states under physiological conditions. There are also subtler categories of disorder, such as conditional (or dormant) disorder and partial disorder. Both the ability of a protein/region to fold into a well-ordered functional unit or to stay intrinsically disordered but functional are encoded in the amino acid sequence. Structurally, IDPs/IDPRs are characterized by high spatiotemporal heterogeneity and exist as dynamic structural ensembles. It is important to remember, however, that although structure and disorder are often treated as binary states, they actually sit on a structural continuum.

Synaptopodin family of natively unfolded, actin binding proteins: physical properties and potential biological functions

The synaptopodin family of proteins consists of at least 3 members: synaptopodin, the synaptopodin 2 proteins, and the synaptopodin 2-like proteins. Each family member has at least 3 isoforms that are produced by alternative splicing. Synaptopodin family members are basic proteins that are rich in proline and have little regular 2° or 3° structure at physiological temperature, pH and ionic strength. Like other natively unfolded proteins, synaptopodin family members have multiple binding partners including actin and other actin-binding proteins. Several members of the synaptopodin family have been shown to stimulate actin polymerization and to bundle actin filaments either on their own or in collaboration with other proteins. Synaptopodin 2 has been shown to accelerate nucleation of actin filament formation and to induce actin bundling. The actin polymerization activity is inhibited by Ca2+-calmodulin. Synaptopodin 2 proteins are localized in Z-bands of striated and heart muscle and dense bodies of smooth muscle cells. Depending on the developmental status and stress, at least one member of the synaptopodin family can occupy nuclei of some cells. Members of the synaptopodin 2 subfamily have been implicated in cancers.