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Analysis of three distinct Ly6-A-related cDNA sequences isolated from rat kidney
S Friedman1, R G Palfree, S Sirlin
1Memorial Sloan-Kettering Cancer Center, New York, NY 10021.
Abstract:
Mouse Ly6A and Ly6C cDNA probes were hybridized to total RNA of rat tissues and, as in mouse, the highest level of Ly6-related transcripts was detected in kidney. Therefore, Ly6-related cDNA clones were isolated from a commercial rat kidney cDNA library in lambda gt11. Four of these (RK3, RK6, RK10, and RK11) have been fully characterized, and represent transcripts from three distinct genes. Each contains a reading frame encoding an amino acid sequence typical of the known Ly6 molecules: a 26aa leader (except in clone RK6 which has only two of its leader codons), followed by a sequence of 108 or 109aa containing 10 cysteines in excellent alignment with those of Ly6A. The three rat polypeptide sequences were more closely related to Ly6A than Ly6C, and more closely related to each other than to Ly6A. The most striking similarity between all these sequences is in the last 33aa at the C-terminal. Most of this is presumed to be cleaved off during post-translational addition of a phosphatidylinositol-glycan (PI-G) membrane anchor. Southern blot analysis of rat DNA probed with rat-Ly6 cDNA showed multiple band patterns indicative of a multigene family. No restriction fragment length polymorphism (RFLP) was evident amongst the six inbred rat strains tested. Anomalies in two of the rat cDNA clones, resulting from improper splicing of the original transcripts, correlated with Ly6Ca exon boundaries, thus suggesting conserved intron-exon organization.
Insights
Researchers identified novel rat Ly6 gene transcripts in kidney tissue. These findings reveal a multigene family with conserved features, suggesting potential roles in cellular functions.
Area of Science:
- Molecular Biology
- Genetics
- Immunology
Background:
- The Ly6 gene family encodes cell surface proteins involved in immune regulation and cell differentiation.
- Previous studies identified Ly6A and Ly6C in mice, with high expression in the kidney.
Purpose of the Study:
- To characterize Ly6-related gene transcripts in rat kidney.
- To investigate the genetic organization and evolutionary relationships of rat Ly6 genes.
Main Methods:
- Hybridization of mouse Ly6A and Ly6C cDNA probes to rat RNA.
- Isolation and characterization of rat kidney cDNA clones (RK3, RK6, RK10, RK11).
- Southern blot analysis of rat DNA and sequence analysis of cDNA clones.
Main Results:
- Highest levels of Ly6-related transcripts were found in rat kidney, similar to mice.
- Four cDNA clones representing three distinct rat Ly6 genes were identified.
- Rat Ly6 sequences showed high similarity to mouse Ly6A, particularly in the C-terminal region.
- Southern blot analysis indicated a multigene family for Ly6 in rats.
- Conserved intron-exon organization was suggested by splicing anomalies in cDNA clones.
Conclusions:
- Rat kidney expresses multiple Ly6 gene transcripts, indicating a complex Ly6 gene family.
- The identified rat Ly6 genes share conserved structural and sequence features with mouse Ly6 molecules.
- The findings suggest conserved functional roles for Ly6 proteins across species.