Principles: Where to find structure of CD22 receptor?

Question

[jwitos]

Hi there, I'm new to bioinformatics so I've got most likely simple question.

So I've been trying to obtain how does the B-cell CD22 receptor (P20273) looked like. I tried the UniProt database, although there is no structure of it: http://www.uniprot.org/uniprot/P20273

I also looked into NCBI Structure db, no entries there as well.

I noticed there are a few isoforms, so I can get their nucleotide sequence, but... there are some drugs designed that target CD22 receptors, so somehow they got to know how does the structure look like? I got the aa structure of isoform CD-22 beta right here:

http://www.uniprot.org/blast/?about=P20273-1

still, no structure. Does that mean that this protein 3D structure is unknown? If yes, how were scientists able to find antibodies anti-CD22? Papers say that the drug "binds to CD22-extracellular domain, with an affinity of KD = 0.7 nM". DrugBank didn't help me either.

Any help will be really appreciated.

[Pierre Lindenbaum]

"If yes, how were scientists able to find antibodies anti-CD22?

See: https://en.wikipedia.org/wiki/Monoclonal_antibody

Luckily, we don't need a 3D structure to get an antibody:

[jwitos]

Thank you! Thus, we can only predict the 3D structure of that receptor?

[Pierre Lindenbaum]

I don't know, you need to search pubmed for this protein. About the domains: the domains are known because they look like a domain of another known protein or some parts of the protein have some biochemical properties: e.g: resistant to proteinase-K == inside the cell.

[Devon Ryan]

There are no structures in PDB, so it seems that no one has solved one yet. As Pierre mentioned, making antibodies is pretty straight forward and requires 0 structure knowledge. Likewise, determining Kd also requires essentially no knowledge of the exact structure.