Isolation and characterization of Japanese eel prolactins.
A highly purified prolactin (PRL) was isolated from the pituitary of the Japanese eel (Anguilla japonica) by extraction with acid-acetone, gel filtration on Sephadex G-75, and reversed-phase HPLC on TSK-gel ODS 120T and on TSK-gel TMS 250. Eel PRL is comprised of two variants (ePRL I and II), which were separated by HPLC on an ODS column. The two PRLs were also secreted by organ-cultured pituitaries in a defined medium. After being dialyzed against distilled water and lyophilized, the medium was dissolved in 0.01 M ammonium acetate (pH 9.0), and then the insoluble fraction was subjected to HPLC on an ODS column to isolate the secreted PRLs. The ePRL I and II were equipotent in retaining plasma Na in the hypophysectomized killifish, Fundulus heteroclitus, transferred from sea-water to fresh water. The putative PRL-producing cells in the rostral pars distalis of the eel pituitary were specifically stained with the antiserum against the mixture of ePRL I and II. Both PRLs had a molecular weight of 22 kDa in SDS-PAGE, an isoelectric point of 10.1 by gel electrofocusing, and an N-terminal residue of valine. Amino acid compositions and the partial amino acid sequences of ePRL I and II show that they are highly homologous with a limited number of substitutions, and that they are more closely related to those of teleostean PRLs than to those of mammalian PRLs.
Suzuki
R
R
Ocean Research Institute, University of Tokyo, Japan.
Yasuda
A
A
Kondo
J
J
Kawauchi
H
H
Hirano
T
T
D000595:Amino Acid Sequence; D000596:Amino Acids / Q000032:analysis; D000811:Anguilla / Q000378:metabolism*; D000818:Animals; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002850:Chromatography, Gel; D002851:Chromatography, High Pressure Liquid; D004591:Electrophoresis, Polyacrylamide Gel; D007016:Hypophysectomy; D007150:Immunohistochemistry; D007526:Isoelectric Point; D008969:Molecular Sequence Data; D008970:Molecular Weight; D009924:Organ Culture Techniques; D010902:Pituitary Gland / Q000737:chemistry; D011388:Prolactin / Q000737:chemistry / Q000302:isolation & purification*
D000596:Amino Acids; D011388:Prolactin