What substance joins proteoglycans together into gigantic complexes called proteoglycan aggregates? these complexes can occupy very large volumes. hyaluronidase hyaluronic acid proteoglycase fibronectin?

That would be hyaluronic acid

Answer;

Hyaluronic acid

Hyaluronic acid are the substances that joins proteoglycan together into gigantic complexes called proteoglycan aggregates.

Explanation;

Proteoglycan aggregates are the major structural components of the extracellular matrix of the cartilage, comosed of aggrecan, hyalutonana and a link protein.

They provide cartilage with gel-like property and resistance to deformation through water absorption.