May act as a carrier of hyaluronan in serum or as a binding protein between hyaluronan and other matrix protein, including those on cell surfaces in tissues to regulate the localization, synthesis and degradation of hyaluronan which are essential to cells undergoing biological processes. I-alpha-I plasma protease inhibitors are assembled from one or two heavy chains (HC) and one light chain, bikunin. Pre-alpha-inhibitor (P-alpha-I) is composed of ITIH3/HC3 and bikunin. Expressed in both liver and brain. Heavy chains are linked to bikunin via chondroitin 4-sulfate esterified to the alpha-carboxyl of the C-terminal aspartate after propeptide cleavage. Belongs to the ITIH family. Truncated N-terminus. Truncated N-terminus.