Screening proteomics found a tremendous drop in the joint lubricant called lubricin, which is a very large and slippery molecule that sits on surfaces and allows the long bones to glide on each other because the cartilage is lubricated. And there’s another molecule called superficial-zone protein which is very similar to lubricin but it’s not secreted in great amounts into the blood so it’s harder to detect. But these are closely related lubricants.
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Lubricin as a factor in gout
American Buddhist Net 