User:Kvaruca/sandbox

RLL comments
This is still pretty rough. You should add more subheadings. You need additional categorization of propellers both in terms of structure and function. There are review articles on this subject that can help guide you.

 Lead 

A beta propeller is a protein structural domain consisting of beta-sheets which are made up of anti-parallel beta strands. These sheets are arranged like the blades of a propeller and together form a funnel-like active site that can interact with other proteins. There are five classes of beta propellers, each of which is highly symmetrical with 4-8 beta-sheets.

 Structure 

A beta propeller is a protein structure consisting of several beta-sheets, each with four anti-parallel beta strands. These sheets are arranged circularly, and point outwards on one end like the blades of a propeller, to form a central tunnel. Loops between individual beta-strands come together at one end of the tunnel to form a funnel-like active site.

The formation of this tunnel yields pseudo-symmetric axes for the domain. Each sheet twists slightly inward so that the first and fourth sheets are almost perpendicular to each other. There are five classes of beta-propellers, each arrangement being a highly symmetrical structure with 4-8 beta sheets.

The structure of this protein domain is mainly stabilized by hydrophobic interactions between the beta sheets. Additional stabilizing interactions can come from hydrogen bonding between the N- and C-terminals of the domain as well as disulfide bonds between the first and fourth blade, the latter mainly being seen in the 4-bladed beta-propeller.

 Function 

 Clinical 

Beta-propeller protein-associated neurodegeneration (BPAN) is a condition characterized by early onset seizures, developmental delays, intellectual disability, and with age, muscle and cognitive degeneration. Variants of the WDR45 gene have been identified in both males and females with this condition.

 original draft  A beta propeller is a protein structure consisting of several beta-sheets, each with four anti-parallel beta strands. These sheets are arranged circularly, and point outwards on one end like the blades of a propeller, to form a central tunnel. Loops between individual beta-strands come together at one end of the tunnel to form a funnel-like active site for substrates or as a place to interact with other proteins. The formation of this tunnel yields pseudo-symmetric axes for the domain. Each sheet twists slightly inward so that the first and fourth sheets are almost perpendicular to each other. There are five classes of beta-propellers, each arrangement being a highly symmetrical structure with 4-8 beta sheets.

The structure of this protein domain is mainly stabilized by hydrophobic interactions between the beta sheets. Additional stabilizing interactions can come from hydrogen bonding between the N- and C-terminals of the domain as well as disulfide bonds between the first and fourth blade, the latter mainly being seen in the 4-bladed beta-propeller.

The beta-propeller protein structure has an active site in the center opening of the propeller, which can bind ligands or other molecules. This aids in protein-protein interactions. Proteins with a beta-propeller can act as catalysts and perform a wide variety of other biological functions. The beta-propeller is known for its plasticity, being able to accommodate a variety of proteins in its tunnel, as well as the uncommon but natural addition or subtraction of beta-strands per sheet, yielding sheets with 3 and 5 strands respectively.

Modelling of beta-propeller structures within proteins by Murzin suggests that the beta-propeller prefers the

The first known beta-propeller structure was in a portion of the enzyme neuraminidase in the influenza virus, which contains six beta sheets.