volume 10 Number 131982 Nucleic Acids Research Complete nucleotide sequence of a sea urchin actin gene

He have determined the complete nucleotide sequence of a sea urchin actin gene, Including the entire protein-coding sequence, Introns and ap-proximately 500 and 700 nucleotides adjacent to protein-coding-sequence on the 5 ' and 3 ' sides, respectively. This gene Is split between codons 121 and 122 and within codon 204 by two Introns which are 233 and 181 nucleo-tides 1n length, respectively. Comparison of the sequence of the two In-trons Indicates a region of distant relatedness which covers about 25 % of their lengths, suggesting that these sequences might have derived from a cannon ancestral sequence. The encoded ami no acid sequence, which matches closely with that reported for actins from other species, 1s more cyto-plasmic-like than muscle-Uke when compared to vertebrate act 1ns. Analysis of the coding-flanking regions Indicates the presence of sequences similar to those thought to be Important for Initiation of transcription and poly-adenylation of mRNA. The location of these sequences and the size of an actin mRNA, transcribed from this or a very closely related gene, suggests that Initiation occurs 347 nucleotides 51 of coding and polyadenylation approximately 515 nucleotides 31 of coding