Lambda2 light chains in normal mouse immunoglobulins.

Abstract

("constant" domain; 6,7,8). The more prevalent A chains were designated.A1, and L315 was tentatively designated a A2 chain (7,8), implying that there are other L chains with the same constant domain.To search for A2 chains in normal mouse Igs we exploited the expectation that a tryptic digest of a mixture of K, Al, and X2 chains would yield the respective COOH-termini as lysine-and arginine-free peptides with the sequences shown in Fig. 1. In the present study these peptides were synthesized (9) and procedures were developed for separating their S-carboxymethyl (CM) derivatives. From ['4C]CM-labeled L chains were dialyzed against 0.25 M acetic acid, freeze-dried, dispersed at 10 mg/ml in 0.2 M NH4 HCO3, pH 8.2, and digested with trypsin (diphenylcarbamyl chloride-treated, Sigma) at 1:50 (wt/wt; for 18 hr at 370). The digest was freeze-dried and taken up in the first buffer of the peptide map (Fig. 2). Then a volume containing 0.25-1.0 mg of digested L chains was spotted on a 20 X 20-cm Eastman thin-layer cellulose plate (no. 13225). The plate was equilibrated for 1 hr with the lower phase and then developed with the upper phase of 1-butanol/acetic acid/water, 4:1:5 (vol/vol). After the plate was dried it was subjected to electrophoresis in the perpendicular direction (130 min, 800 V) with pyridine/acetic acid/water (25:25:950), pH 4.8, as buffer.[14C]Peptides [detected by contact radioautographs with Kodak XR-1 film (X-omat R) for 40 hr at -80°] were eluted from the maps with 0.5 ml of 0.3% NH40H; after freeze-drying they were subjected to additional electrophoresis on thin-layer cellulose at pH 6.5 with pyridine/acetic acid/water (100:4:896) and at pH 1.9 with acetic acid/formic acid/water (80:20:900).

On a regulatory gene controlling the expression of the murine lambda1 light chain.

“…--, not done. * Our data show a lower )kl:x-ratio than that reported in a recent study (14) using radiochemical determination of carboxyl-terminal peptides. While this difference does not affect our interpretations of the findings, the reason for the discrepancy remains to be clarified.…”

“…In this regard, it should be noted that although the )h and 2~2 light chain class are probably each coded for by one v and one c gene, the ~1:~2 ratio in normal Ig is 4:1 (14). The difference in expression could be accounted for by a difference in the efficiency of translocation for ~x and ~2.…”

Identification of a third type of lambda light chain in mouse immunoglobulins.

“…In this study we examined six light chains that, on the basis of antigenic properties and a characteristic COOH-terminal tryptic peptide, were previously considered to have the same constant region as L315 and were thus identified as A2 chains (2,6,8). Based on cleavages at methionine residues, four of these chains (L49, L8-47, L72, and L'5), designated as A3 chains, were found to share distinctive constant region features that differentiate them from A2 and Al, the other types of A chains.…”

“…Chains with the constant region of L'04 are called Al (or Al); those with the constant region of L315 are called A2 (or A,,) (3). Analyses of antigenic properties and of the COOH-terminal peptides obtained by tryptic digestion of light chains showed that in most strains of mice about 1% of normal serum immunoglobulins have A2 chains and about 4% have Al chains (2,6). We show here that some light chains previously considered to be A2 are another type ofA chain, which we designate as A3 (or Al,,).…”

Analysis of the Virus-Specific and Nonspecific B Cell Response to a Persistent B-Lymphotropic Gammaherpesvirus

“…1 and 2), measured as the number of lymphocytes producing Ig containing the light chain. Such lymphocytes represent ϳ90 -95% of AFC in normal mice (40). The virus-specific assays applied in this study used purified, disrupted virions as target Ags.…”