Primary structure of a monoclonal κ chain in myeloma with light chain deposition disease
1992; Oxford University Press; Volume: 87; Issue: 1 Linguagem: Inglês
10.1111/j.1365-2249.1992.tb06424.x
ISSN1365-2249
AutoresAhmed Amine Khamlichi, Pièrre Aucouturier, Christine Silvain, Marc Bauwens, Guy Touchard, J-L PREUD'HOMME, François Nau, Michel Cogné,
Tópico(s)Glycosylation and Glycoproteins Research
ResumoSUMMARY Previous data suggest that structural abnormalities of immunoglobulin light chains may be responsible for non-amyloid light chain deposition disease (LCDD). We report on the complete primary sequence deduced from complementary (c)DNA analysis of a normal-sized κ chain in a case of myeloma-associated LCDD. The patient's urine contained a κ type Bence-Jones protein made of monomers and dimers of an unglycosylated κ chain. The bone marrow myeloma cells contained intracellular κ and γ chains by immunofluorescence. Biosynthesis experiments showed the production of normal-sized γ chains and of κ chains with the same apparent molecular mass (Mr) in SDS gels as the urinary κ chain (26000–27000). These κ chains were secreted as assembled IgG molecules and as a large excess of free monomers and dimers. The complete sequence of two identical cDNA clones derived from a normal-sized κ messenger RNA indicated that this K chain belonged to the rare VκIV subgroup. The κ mRNA had an overall normal structure made up of the VκIV sequence rearranged to JκIV and followed by a normal constant exon of the Km(3) allotype. The variable region differed from the VκIV-JκI germline sequence by 17 amino acid substitutions. The peculiar sequence of the variable region of this κ chain of a rare subgroup might relate lo its tissue deposition.
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