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

Abstract

Sequence analysis of an 1gM immunoglobulin shows that the variable regions of hunman micro and gamma1 heavy chainis may have twice as much homology as their constant regions and that evolutionary divergence of micro and gamma1 heavy chain genes occurred not long after the separation of heavy and light chain genes.

Amino acid sequences at constant and variable regions of heavy chains of monotypic immunoglobulins G and M of a single patient

“…Results of the amino acid sequence analyses are shown in Table II. The amino acid sequences for the Nterminal 38 residues of the Fc^(Til) is identical with that of another IgM protein (Ou) reported by Shimizu et al (1971).…”

“…Til yl VHIII Glu-Val-Gln-Leu-Leu-Glu-Ser-Gly-Gly-Gly-Leu-Val-Gln-Pro-Gly-Gly-Ser-Leu-Arg-Leu-Ser-Cys-Ala-Ala-Ser Til µ VHIII---------------Nie 1 VHIII PCA--Val-Gin---Val----Arg------------------Eu 1 VHI PCA---Val-Gin-Ala-Glu-Val-Lys-Lys------Ser--Val-Lys-Val----Lys-------------Ou µ VHII PCA-Thr--Thr-Pro-Ala--Lys---Lys-Gln-Pro----Thr--Thr--Thr-Phe--Cor VHII PCA-Thr--Arg---Pro-Ala--Lys--Thr-Gln-Thr--Thr--Thr--Thr-Phe-------Daw 7I VHII PCA-Thr---Arg---Pro-Ala--Arg---Thr-Gln-Thr--Thr--Thr-Thr-Phe---He 7I VHII PCA-Thr---Lys---Asn--Pro-Thr----Lys---Thr-Glu-Thr--Thr---Thr--Thr-Leu--- ----------------------Nie 7I VHIII Asp-Ser-Lys-Asn-Thr-Leu-Tyr-Leu-Asn-------Pro-Glx-Asx--------------Arg Eu 7I VHI Glu-Ser-Thr-Asn-Thr-Ala-Tyr-Met-Glu-Leu-Ser------Ser---------Phe-Phe---------Gly ------------Thr--------------- " Residues are numbered after the sequence of Eu. References for the sequences are: Til 2 and µ (Wang et al, 1971, and this paper), Nie (Ponstingl et al, 1970), Eu (Edelman et al, 1969), Ou (Shimizu et al, 1971), Cor and Daw (Press and Hogg, 1969), and He (Cunningham et al, 1969). Solid lines indicate identity to the seqence of Til 72 on the top line.…”

Initiation of Protein Synthesis at an Unusual Position in an Immunoglobulin Gene?

“…Comparable data for IgG2 and IgG3 heavy chains are limited to 17 and 18 residues respectively (11), but at these positions all four IgG immunoglobulins are the same, having six residues identical with 82-microglobulin. Of 18 residues known in these regions for immunoglobulin M (IgM) (12), only one is the same as /82-microglobulin (compared to 10 of the comparable 18 IgG positions). No sequence data are yet available in these regions for other classes of immunoglobulins.…”

Heavy-chain variable-region sequence from an inulin-binding myeloma protein

“…a H3 begins three residues after the invariant Cys at position 96 and ends at the fourth residue before the relatively constant Trp at position 108 (Rudikoff and Potter, 1974;Capra and Kehoe, 1974a). Mouse sequences are as follows: M603, Rudikoff and Potter (1974); T15 and M167, Rudikoff and (1970); Ou, Shimizu et al (1971);Eu, Edelmar, et al (1969); Gal, Watanabe et al (1973); BS-5 and K-25, Jaton (1975). 6 PC = phosphorylcholine; DNP = dinitrophenol.…”