β₂-Microglobulins

Abstract

It is little wonder that when Berggård and Beam isolated β ₂-microglobulin (β ₂ − μ) from urine in 1968, the report did not create a major sensation among the students of proteins, especially since no function could be found for this small-molecular-weight material at that time. Furthermore, urine was considered to be waste, even though it contains a multitude of products which cannot be obtained by the researcher otherwise. The partial amino acid sequence established by Smithies and Poulik (1972a) provided direct evidence that β ₂ − μ is related structurally and ontologically to immunoglobulins, and stimulated interest in the substance. As judged by the complete amino acid sequences reported by Peterson et al. (1972) and Cunningham et al. (1973), it became evident that β ₂ − μ might be of greater immunological importance than previously realized. Demonstration of its presence in cell membranes (Poulik and Motwani, 1972; Peterson et al., 1972, and Bernier and Fanger, 1972) subsequently led to recognition of the close association of β ₂ − μ with human histocompatibility (HL-A) antigens (Nakamuro et al., 1973; Grey et al., 1973, Peterson et al., 1974). The true structural arrangement of the HL-A β ₂ − μ complex may remain controversial for some time, but it is vigorously being investigated. Methods for isolating the complex are being sought (Poulik et al., 1974a; Reisfeld et al., 1974) in order to purify HL-A antigens and to establish their structure.