THE FOLLICLE-STIMULATING-HORMONE BETA-SUBUNIT GENE OF THE COMMON BRUSHTAIL POSSUM (TRICHOSURUS-VULPECULA) - ANALYSIS OF CDNA SEQUENCE AND EXPRESSION

Reverse transcription-PCR has been used to obtain a cDNA sequence from the follicle-stimulating hormone (FSH) beta-subunit gene of the Austr alian brushtail possum (Trichosurus vulpecula). Comparisons of the pos sum FSH beta-mRNA coding region nucleotide sequence with that of six e utherian mammal homologues reveals a mean percent identity of 77.3% an d 76.8% at the nucleotide and predicted amino acid-sequence levels res pectively. Furthermore, the predicted amino acid sequence of the possu m FSH beta mature protein shows evolutionary conservation of twelve cy steine residues and two potential N-linked glycosylation sites. The pr otein lacks the CAGY motif present in most reported glycoprotein beta- subunit sequences. The translation termination codon and consensus pol yadenylation sequence overlap, a feature observed in other mammalian F SH beta genes. Northern hybridization of total RNA from adult female p ossum pituitary revealed three hybridizing transcripts of approximatel y 2.8, 1.2 and 0.5 kb which may arise from utilizing alternative polya denylation signals. In situ hybridization localized the FSH beta trans cripts to a sub-population of anterior pituitary cells interpreted as being gonadotropes. In summary the results indicate considerable evolu tionary conservation of the structure of the FSH beta-subunit gene bet ween the marsupial and eutherian mammalian lineages.