Macroglobulin Structure: Variable Sequence of Light and Heavy Chains

Abstract

The variable regions of the light and heavy chains on the same macroglobulin (immunoglobulin M) molecule are no more related in amino acid sequence than are the variable regions of the light and heavy chains of different immunoglobulin molecules. Subgroups of micro chains are similar in their variable sequence to subgroups of gamma chains.

Interchain and Intrachain Disulfide Bridges of a Human Immunoglobulin M: Detection of a Unique Fragment

“…Counting from the N-terminus, the first of these four half-cystine residues is involved in the H-L bridge, as shown by our diagonal electrophoresis and previously (11)(12)(13). The second half-cystine participates in a A-u bridge linking the two halves of the pepsin fragment (Fab') 21A, and is probably located in the "hinge" region (12,16,20).…”

“…Table 1 lists the partial sequences of the major CMCyscontaining peptides. Their function appears to be as follows: Ppt-TP corresponds in composition to the previously identified bridge between heavy and light chains (11)(12)(13). It was shown to be in the same region as the C-terminal end of the light chain on a diagonal map of the pepsin-trypsin digest of the intact protein and was therefore presumably bridged to it.…”

Variation and Homology in the Mu and Gamma Heavy Chains of Human Immunoglobulins

“…This conclusion is based (i) on the strong homology of VIIII subgroup proteins just prior to the onset of the constant region, (ii) on the homology to the yl constant region shown in Fig. 2, and (iii) on the fact that the sequence around the disulfide bridge at Cys-140, between the light and heavy chains, is the same for at least four different p. chains that we and others (2,20) have studied. Of course, complete sequence analysis of several p, chains (which we are doing) will be required to establish the exact point of division between the VI, and CII regions of human p, chains.…”

Sharing of Individual Antigenic Determinants Between a G and a M Protein in the Same Myeloma Serum

“…The heavy chains of human immunoglobulins have been classified into four different variable region subgroups according to amino acid sequence homologies of the N-terminal segment (16). These amino acid homologies of the heavy chain have accounted for as high as 70% of all the amino acids of the variable region.…”