Large Molecular Size Prolactin with Reduced Receptor Activity in Human Serum: High Proportion in Basal State and Reduction after Thyrotropin-Releasing Hormone*

Discrepancy between immunoactivity and bioactivity of big-big and big human growth hormones in acromegaly.

“…Big form hGH has been characterized by RRA before and after mercaptoethanol and urea treatment and it has been suggested that big form is a dimer of hGH molecule linked by disulfide bonds and has less receptor activity (Gordon et al, 1973b ;Garnier at al., 1978 ;Farkouh, 1979). Our studies also showed that big hGH had almost half the bioactivity of little hGH as shown by Nb2 lymphoma cell bioassay, which was similar to the reported results of RRA.…”

“…A big form which elutes between void volume and little form on Sephadex G-100 column has been characterized as two peptide chains linked by a disulfide bond (Wright et al, 1974 ;Benveniste et al, 1975 ;Schneider et al, 1975 ;Benveniste et al, 1979). Bioactivity of the big form has been investigated using radioreceptor assay (Shiu et al, 1973 ;Tsushima and Friesen, 1973) and decreased reactivity has been observed (Gordon et al, 1973b ;Gamier, 1978 ;Farkouh et al, 1979).…”

“…Japon. April 1984 As to the big-big form, which elutes at void volume, Farkouh et al (1979) reported that big-big hPRL has about 15 % of the receptor activity of little hPRL.…”

Characterization of “Big Big Prolactin” in Serum and Tumor Extract in Patients with PRL-Secreting Tumor

“…The gel filtration patterns of PRL in serum and pituitary extract have been reported to consist of three peaks, i. e. "little PRL" in the fraction corresponding to PRL monomers, "big PRL" in the fraction corresponding to PRL dimers or trimers, and "big big PRL" in the vicinity of the void volume (Fang and Refetuff 1978;Farkouh et al, 1979Gamier et al, 1978Jackson et al, 1985;Kiefer and Malarkey 1978;Rogol and Rosen 1974;Whittaker et al, 1981). It has also been demonstrated that "big PRL" is PPL polymerized by means of the disulfide bonds (Benveniste et al, 1979).…”

Pregnancy and pituitary disorders

“…Big big PRL is reported in a range of 8-38% of total PRL during pregnancy (57)(58)(59). Frequency of macroprolactinemia during pregnancy is reported as 2.9-3.8% due to anti-PRL autoantibodies (60,61).…”