Human beta two microglobulin: Difference between revisions

From Proteopedia
Jump to navigationJump to search
← Older editNewer edit →
Jia Dong (talk | contribs)
32 edits
No edit summary
Jia Dong (talk | contribs)
32 edits
No edit summary
Line 21: Line 21:
==Structural comparison of MHCb2m and Mhb2m==
==Structural comparison of MHCb2m and Mhb2m==


[[Image:Human b2m bound to MHC-1 .jpg.jpg]]      [[Image:Momeric human b2m.png]] 


Fig.1. crystal structures of MHCb2m (left) and Mhb2m (right)


Both of the two strucures adopt seven-stranded β sandwich fold with a short C' β strand located in the loop connecting strands C
Both of the two strucures adopt seven-stranded β sandwich fold with a short C' β strand located in the loop connecting strands C
Line 31: Line 29:
His-51 (which points inwards in the structure of MHCb2m) rotates by approximately 180, such that it now points away from the hydrophobic core of the protein. This would remove the second protevtive feature from the edge strand, facilitating further interaction in this region (Fig.2).
His-51 (which points inwards in the structure of MHCb2m) rotates by approximately 180, such that it now points away from the hydrophobic core of the protein. This would remove the second protevtive feature from the edge strand, facilitating further interaction in this region (Fig.2).


[[Image:His51.jpg]]


Fig.2. Ribbon diagram showing the position of HIs-51 in the crystal structure of Mhb2m (left) and MHCb2m (right)


=Amyloid Fibril formation of Mhb2m=
=Amyloid Fibril formation of Mhb2m=
Line 51: Line 47:




 
==Fibrillar architecture===
[[Image:Conformation change of P32A.png]]
 
Fig.3. summary of hydrophobic side chain differences resulting from a ''trans'' backbone at position 32
 
===Fibrillar architecture===
In aqueous solution at neutral or acidic condition, amyloid-like fibrils are formed from b2m that show a long-straight, left-hand twisted and unbranched morphology when observed by EM and AFM (Fig.4)
In aqueous solution at neutral or acidic condition, amyloid-like fibrils are formed from b2m that show a long-straight, left-hand twisted and unbranched morphology when observed by EM and AFM (Fig.4)


[[Image:Fibrillar architecture neutral.png]]    [[Image:Acidic.png]]
Fig.4. Comparison of experimental data for fibrils of b2m formed at pH 7.0(a) and 2.5(b). EM scale bar indicates 100 nm


===A unifying mechanism of b2m fibril formation===
===A unifying mechanism of b2m fibril formation===
Line 69: Line 58:




[[Image:Unifying mechanism.png]]


Fig.5. Scheme for convergence of the mechanisms of fibril formation at pH 2.5 and 7.0. Regions with high amyloidogenic propensity  are displayed in pink. It is not known precisely how oligomers stack or whether they have ordered b-sheet, however, increased intermolecular protein–protein interactions (red) may be important in the reaction pathway.
 




Retrieved from "https://proteopedia.org/Human_beta_two_microglobulin"