The heavy chain variable portion of mouse myeloma protein MOPC-3 15 (a, h z ) was obtained from its Fv fragment (J. Hochman, D. Inbar and D. Givol, Biochemistry 1973. 1 2 : 11 30.) and was used t o immunize rabbits. Rabbit anti-V, antibodies precipitated V,, Fv and the intact protein 315. The V, region specificity of these antibodies was evident from the line of identity in agar gel diffusion between Fv and M315, and from the lack of precipitation with another (11 chain of XRPC-25 or with light (L) chains. Radioimmunoassay binding and inhibition studies demonstrated that anti-VH 31 5 antibodies cross-react with heavy (H) chains derived from various mouse myeloma proteins (MOPC-460, XRPC-25, MOPC-I 04E, UPC-10, TEPC-15, HOPC-8, MOPC-167) as well as with H chains derived from mouse IgG. These H chains can inhibit 90-100 % of the binding of VH3 15 by anti-VH indicating extensive sharing of antigenic determinants by various VH regions. The relative affinity of anti-V, for various H chains was 20-1 000-fold weaker than its affinity for the MOPC-3 1 5 H chain. The cross-reaction of the various H chains was independent of antibody specificity, subclass, subgroup or considered as anti-V framework antibody.Anti-VH315 cross-reacts with isolated H chains but not with intact molecules and can therefore be used t o detect VH determinants only in the absence of chains.allotype. This suggests that anti-VH may be

No abstract

No abstract

No abstract

We present a statistical method for detection of palindromes in mRNA or DNA, starting from the protein sequence. Analysis of immunoglobulin genes by this method demonstrates that palindromic se uences are not randomly distributed. They are located at each side of the hypervariable regions in the variable (V) genes, whereas no such regular design is observed in the constant (C) genes. In addition, palindromic sequences overlap the V-C junction in all immunoglobulin classes and significant palindromes are present near residue 216 of the heavy chain, which is the end of deletions in many heavy chain diseases. The relevance of these palindromes to gene translocation and generation of diversity in antibodies is discussed.A palindromic DNA sequence possesses a 2-fold rotational axis of symmetry perpendicular to the-helix and, as a consequence, the base sequences of the two strands are identical when read in the same polarity:Such DNA sequences are universally distributed and have been shown to exist in bacteriophages (1, 2), in Escherichia coli plasmids (3), and in eukaryotic DNA (4). They can be rather long (300-1200 nucleotide pairs), and some are able to form hairpin-like structures in single-stranded DNA (4). They can also be found in heterogeneous nuclear RNA (5), which is characterized by its resistance to RNase. It has been suggested (6) that their structure (cruciform-like DNA) might be a recognition site for proteins acting at the DNA level; on this basis, molecular models for genetic recombination have also been proposed (7). These speculations are supported by several findings: the Lac operator is double stranded and about 27 base pairs long; and the sequence of its RNA transcription copy has been determined (8) and contains a partial 2-fold rotational symmetry. In phage X, the gene cl is surrounded by three left operators and three right operators. Each operator has an axis of partial 2-fold symmetry (9). Inverted repeats have been found in transposable DNA segments of bacteria (10,11 pointed out that palindromic sequences may occur near the V-C junction and that these sequences could be recognition sites for enzymes involved in the translocation process (14).In this paper, we present a method for detection of palindromes in mRNA, starting from the protein sequences. The method is applied to the case of immunoglobulins, and we show that the palindromic sequences are not randomly distributed but are located preferentially at the boundary of hypervariable regions and near the V-C junction. METHODS The searching procedure is an extension of Fitch's polypeptide comparison method (15): the protein sequence is translated into its degenerate mRNA sequence, which is then analyzed for the presence of palindromes. This analysis is performed by matching, in a sliding process, each subsequence of 11 nucleotides (polarity 5'-3') with all the possible consecutive subsequences of 11 nucleotides (polarity 3'-5'). For each match, a complementation index and its probability for occurring by chance are computed and ...