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Caveolin‐1 isoforms are encoded by distinct mRNAs
Author(s) -
Kogo Hiroshi,
Fujimoto Toyoshi
Publication year - 2000
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/s0014-5793(99)01730-5
Subject(s) - gene isoform , messenger rna , exon , microbiology and biotechnology , intron , biology , complementary dna , transcription (linguistics) , northern blot , gene , tata box , rapid amplification of cdna ends , gene expression , promoter , genetics , molecular cloning , linguistics , philosophy
By searching the EST database with the known cDNA sequence encoding α‐caveolin‐1 (full‐length: FL), we found a variant having a hitherto unknown sequence in place of the first exon (5′‐end variant: 5′V). The expression level of 5′V mRNA was equivalent to that of FL mRNA. The entire sequences of FL and 5′V mRNA were determined by 3′‐ and 5′‐RACE analysis; their sizes were 2484 bp and 2533 bp, respectively, and the sequences were identical except for the region of the first exon. By Northern blotting, FL and 5′V mRNAs showed the same tissue distribution, and were intensely expressed in the lung, heart, and skeletal muscle. Analyzing the protein production from these mRNAs using green fluorescent protein as a tag, we found FL mRNA to produce the α‐isoform predominantly, but to form little β‐isoform. The production of the β‐isoform from 5′V mRNA was also demonstrated. By sequence analysis of the first intron of the caveolin‐1 gene, a TATA box was found at 28 bp upstream of the transcription initiation site for 5′V mRNA. This is the first demonstration of caveolin‐1 mRNA variants generated by alternative transcription initiation, and it indicates that the two isoforms of caveolin‐1 are produced from two distinct mRNAs.