User:Elizabeth Tomao/sandbox1 alphaB-crystallin

From Proteopedia

Revision as of 22:07, 8 May 2012

The Mysterious Roles of αβ-crystallin

Introduction

The protein αβ-crystallin is small heat shock protein (HSP) that is part of crystallin family and the α cystisralin subfamily. It is closely related to αA crystalin, there are a few major differences between the two proteins. αA crystallin is mostly found in the ocular lens, whereas αβ-crystallin can be found in the ocular lens but also in other tissues such as the lungs, kidneys, brain, and cardiac muscles. Heat shock proteins may also be known as stress proteins because they are activated under conditions of stress; such as heat, change in pH, amount of oxygen and other materials such as metals. When activated these heat shock proteins act as chaperones, by assisting in the folding and folding and prevent the aggregation of misfolding of other proteins. αβ-crystallin accumulates in tissues when they are exposed to any type stress, therefore it is common in a tissue that is being affected by a disease. It has been found in the following tissues brain, heart, kidneys, skeletal muscle, placenta, and skeletal muscle and associated with such diseases as Parkinson ’s disease, Alzheimer’s Disease, Alexander’s Disease, Multiple Sclerosis, Cancers, and Heart Disease. This small protein acts as a form of defense by preventing the

Structure and Function

Structure

αβ-crystallin is small containing 20kDa that is normally formed into oligomers that are around 600kDa. There are three sections of the αβ-crystallin, the α- crystallin domain (ACD) which is ninty residues long and made of a α sheets folded into a sandwich like formation with β8-β-9β-3(β-2) and β4-β4- β6+7. . On either side of the ACD are the N and C- terminals. The N- terminal (Green Link) is sixty residues long and the C- terminal twenty five residues long (green link). It has been found it is these terminals that are essential for the proper functioning of the αβ-crystallins. Studies conducted by removing parts of the N and C- terminals shoed as decrease in chaperone activity each with their own role in the proper functioning of the αβ-crystallin. The N-Terminal contains a a hydrophobic interactive sequence (41STSLSPFYLRPPSFLRAP58) (green link) which is extremely important in substrate selection. It is the nature of this sequence that recognizes and selects substrates to protect against aggregation based on the amount of protein unfolding. The C- Terminal on the other hand contains a polar interactive sequence (155PERTIPITREE165)( Green Link) which imperative for conserving the solubility of the unfolded proteins.

Active Sites

The sections of the αβ-crystallin are integral to the performance of the protein the terminals merely explain how it is that these little proteins have the ability to prevent apoptosis or mitosis of cancer cells. Much of the funtion of these proteins has to do with where and how they bind to cells, which occurs at numerous binding sites. Many studies have been carried out to determine the binding sites and it wasn’t until recently that scientists unveiled some information about this process. In a pin array study conducted in 2006 by the Mason Eye Institute, where results indicated that sequences 9-20, 43-48, 113-120, 131-138, 141-148 all contribute to the binding of the target proteins.

Function

THe min job of this protein is to

Location

Associations with Diseases

Current Uses

Future Research