Several biosciences companies mention the molecular weight of DRD1 as 49 kDa (Abcam - http://www.abcam.com...dy-ab20066.html) to 75 kDa (Santa Cruz - http://datasheets.scbt.com/sc-1434.pdf). Recent papers confidently believe that DRD1 is at or around 49 kDa (http://www.ncbi.nlm....pubmed/22336227).
Abcam's datasheet at least honestly report thus: "Observed band size : 48 kDa, Additional bands at : 45 kDa,70 kDa,75 kDa. We are unsure as to the identity of these extra bands."
I know that Dopamine receptor antibodies are notorious for poor sensitivity and specificity.
Any help as to what these other bands are and why different companies are confidently claiming the Mol Wt of DRD1 variously as 49 or 75 kDa shall be greatly appreciated.
One interpretation of various band sizes is that DRD1 is forming a heterodimer with another DAR subtype or even another GPCR.
I believe the best explanation of the different bands found on western blots for Dopamine D1 is found in the paper entitled "D1 dopamine receptor signaling involves caveolin-2 in HEK-293 cells" by our collaborators in the Jose Lab. We find the similar set of bands from human renal proximal tubule cells. The bottom line is that the protein is N-glycosylated in at least 3 sites, palmitoylated in one site, and has as many as 15 serine threonine phosphorylation sites. We were so frustrated with the antibodies that we made our own polyclonal. Some lots of Santa Cruz rabbit polyclonal antibodies are even better than ours but they are hit or miss. Epitomics makes a rabbit monoclonal that works very well in our hands, and Cell Signalling worked with us to make two other rabbit monoclonals that work really well, but I don't know when they will be available. I hope that is helpful.
Thanks Josh and John. Will follow up and look up all the references in the paper you have quoted John and get back if I develop some insights :)!
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