Isolation of a rat parvalbumin gene and full length cDNA.

The complete sequence of the rat parvalbumin mRNA was determined by sequencing a near full length cDNA clone and a primer extension product of the 5' untranslated region of this clone. The parvalbumin sequence contained 72 nucleotides of the 5' untranslated region, 333 nucleotides of the coding sequence, and 183 nucleotides of the 3' untranslated sequence in the case of the shorter parvalbumin messenger RNA or 556 nucleotides in the case of the larger parvalbumin messenger RNA. The two RNAs were derived from a single primary transcript since two clones were sequenced which were identical except for the site of polyadenylation. The polyadenylation signal of the shorter, more abundant RNA was AATAAA while the putative signal for the larger RNA was GATAAA. A 32-base pair sequence comprising part of the 5' untranslated region and the first seven codons of the parvalbumin cDNA was 81% homologous to a region of the chicken calmodulin cDNA encoding part of the first Ca2+-binding domain. This homology indicates that this portion of the parvalbumin mRNA may have evolved from a primordial first domain. A parvalbumin genomic clone which hybridized to probes derived from both the coding and 3' untranslated region of the cDNA was cloned from a rat genomic library. Partial sequencing identified an uninterrupted stretch of 585 base pairs identical to the 3' end of the parvalbumin cDNA. Two introns were localized in the genomic clone. Their position with respect to the parvalbumin amino acid sequence corresponded to the intron locations found in genes of several other Ca2+-binding proteins. This result indicates that, despite the deletion of one Ca2+-binding domain, the remainder of the parvalbumin gene has maintained the structural pattern of the Ca2+-binding protein gene family.