What is the protein associated with amyloidosis?

Amyloidosis is a condition characterized by the accumulation of abnormal protein deposits in various tissues and organs. The key protein associated with amyloidosis is beta-2 microglobulin. This protein is a component of major histocompatibility complex (MHC) class I molecules and can accumulate in patients undergoing long-term dialysis, leading to a specific type of amyloidosis known as dialysis-related amyloidosis.

In the context of other proteins mentioned, albumin is a common plasma protein but not associated with amyloidosis. Immunoglobulins are antibodies that play a role in immune response and can sometimes be involved in different types of amyloidosis, but they are not the principal protein identified in this condition. Creatinine is a waste product from muscle metabolism used to assess kidney function, but it does not relate to amyloidosis in terms of protein accumulation.

Therefore, beta-2 microglobulin's direct connection to the development of amyloid deposits highlights its critical role in the pathophysiology of amyloidosis, making it the correct choice for this question.