Alternative splicing of the prolactin receptor gene generates a 1.7 kb RNA transcript that is linked to prolactin function in the red deer testis.

A cDNA encoding a putative non-membrane bound prolactin receptor was amplified by RT-PCR from red deer (Cervus elaphus) testis. Sequence analysis suggests that the testicular cDNA is generated by alternative splicing resulting in the deletion of exons 7 and 8, which code for: (a) the final 53 aa of the extracellular domain of the receptor including the fifth conserved cysteine residue and the WS x WS motif, (b) the entire transmembrane domain, (c) the first three cytoplasmic amino acid residues, and (d) two nucleotides of the fourth cytoplasmic amino acid codon. The resultant RNA would encode a putative protein of 174 aa due to a single bp frame shift and a premature stop codon. Northern blot analysis confirmed that the PCR-amplified cDNA is encoded by a specific 1.7 kb RNA transcript whereas the membrane bound receptor is encoded by transcripts of 3.5 and 2.5 kb. HPLC studies using media from 293 cells transfected with the 1.7 kb cDNA failed to detect any specific binding for prolactin. These data suggest that: (a) the deletion in the 1.7 kb transcript alters the structure of the prolactin binding domain in the putative protein encoded by the 1.7 kb transcript, and (b) alternative splicing of the prolactin receptor gene toward the 1.7 kb transcript is a means of down-regulating the expression of the full length prolactin receptor and hence may modify the role of prolactin in the testis of seasonally breeding mammals such as red deer. The sequence reported in this paper has been deposited in the Genbank/EMBL data base with accession number Y14753.