Sandbox 1498

3BPU is a transferase found in Homo sapiens. It is the 3rd PDZ domain of human membrane associated guanylate kinase Q96QZ7, C677S and C709S double mutant. It is encoded by the MAGI1 gene. [1]

Function

3BPU is involved in the cell signalisation. It may play a role as a scaffolding protein at cell-cell junctions. It may regulate acid-induced ASIC3^[1] currents by modulating its expression at the cell surface through interacting with its PDZ domain. It may also allow the interaction of Q96QZ7 with JAM4, providing an adhesion machinery at tight junctions. This may regulate the permeability of kidney glomerulus and small intestinal epithelial cells.^[2]

Structure

3BPU is mainly made of components which lead to hydrophobic and polar (charged or uncharged) interactions [2]

Primary structure

3BPU is a one chain structure of 88 amino-acids. There are 88 residues. [3]

Secondary structure

3BPU's structure is composed of 10% of (1 left-handed alpha helix; 9 residues, mainly Leu, Met, His, Glu, Gln) and 40% of (8 antiparallel strands; 36 residues, mainly Val, Ile, Trp).

Tertiary structure

3BPU is a membrane-associated protein. It interacts with the membrane thanks to its hydrophobic through hydrophobic interactions.

(Quaternary structure

Do we need the biological unit ?

Biological unit  is the quaternary structure that is believed to be the functional form of a macromolecule. One set of conditions may change under a different set of conditions, so there may be more than one functional form (biological unit) that includes a given protein chain.)

http://oca.weizmann.ac.il/oca-docs/fgij/biounit.htm?3BPU

-> Biomolecule: 1

Author dertermined quaternary structure: Monomeric

This quaternary structure which leads to the function could be influenced by cristal contacts because these one make bonds with the asymmetric unit. [4]

Interactions with ligands

3BPU's ligands are two Zn atoms.[5] The i are polar interactions. His645 and Glu714 interact with a first Zn atom. His699 and Val703 interact with a second Zn atom.

References

1. ↑ http://www.rcsb.org/pdb/protein/Q9UHC3
2. ↑ https://www.uniprot.org/citations/12773569