Haptoglobin,transferrin and serum albumin variants in the Dayaks of Sarawak

Summary The Land Dayaks and the Sea Dayaks of Sarawak were surveyed for haptoglobin, transferrin and serum albumin variants. The Hp¹ gene frequency was 0.385 in 283 Land Dayaks as well as in 205 Sea Dayaks. The TfD_Chi gene frequency in 283 Land Dayaks was 0.030 and in 188 Sea Dayaks it was 0.040. Serum albumin Medan was found in one of the 188 Sea Dayaks.This work was supported in part by the University of California International Center for Medical Research (UC ICMR) through research grant AI 10051, and in part by research grant HL 10486, both from the National Institutes of Health, U.S. Public Health Service.     

Haptoglobin, transferrin and serum albumin variants in the Dayaks of Sarawak.

The Land Dayaks and the Sea Kayaks of Sarawak were surveyed for haptoglobin, transferrin and serum albumin variants. The Hp1 gene frequency was 0.385 in 283 Land Dayaks as well as in 205 Sea Kayaks. The TfDChi gene frequency in 283 Land Dayaks was 0.030 and in 188 Sea Kayaks it was 0.040. Serum albumin Medan was found in one of the 188 Sea Kayaks.     

A study on the intracellular transport of prothrombin, albumin and transferrin in rat

The intracellular transport of prothrombin in rat has been studied and compared with the transport of albumin and transferrin. The proteins were immunoisolated from plasma samples after pulse labelling with [3H]leucine and the secretion kinetics were determined. The half-times for secretion (t1/2) were approx. 30, 53 and 75 min for albumin, prothrombin and transferrin, respectively, whereas the minimal transit time for prothrombin was approx. 30 min, and those for albumin and transferrin 15-20 min. After injection of vitamin K-1 into warfarin-treated rats, the accumulated prothrombin precursor was gamma-carboxylated and secreted with a t1/2 of 37 min. This indicates that the gamma-carboxylation of prothrombin in rough endoplasmic reticulum cannot account for the delay in the transport of prothrombin as compared to albumin. Comparison of the incorporation of [3H]leucine and [3H]glucosamine into plasma prothrombin and transferrin suggested that transferrin is secreted randomly from an intracellular pool, whereas prothrombin is transported in a more orderly sequence. Moreover, treatment of rough microsomes with 0.05% sodium deoxycholate indicated that prothrombin is more tightly associated with the membranes of rough endoplasmic reticulum than albumin and transferrin.     

The acute effect of ethanol on albumin, fibrinogen and transferrin synthesis in the rat

Decrease of absolute synthesis of albumin and fractional synthesis of transferrin was observed within 3h of orally administering ethanol (4ml/kg) to rats maintained on a 40%-protein diet. In contrast, absolute synthesis of fibrinogen was unaffected. With this ethanol intake, the changes in protein synthesis occurred without significant ultrastructural change in the liver. When the ethanol intake was greater (8ml/kg) ultrastructural disruption was observed. However, both the decrease of plasma protein synthesis and the ultrastructural alterations could be prevented by the simultaneous administration of a mixture of amino acids with the ethanol. The latter findings, not reported hitherto, suggest that ethanol may interfere with hepatic plasma protein synthesis and ultrastructure more through a disturbance of amino acid metabolism than through direct physical damage to the hepatocyte. An Appendix outlines the deconvolutional method used to correct for losses of labelled protein in the period during which measurements were made. The principle may also be applied to labelled plasma urea. The details of the calculations are given in a supplementary paper that has been deposited as Supplementary Publication 50007 at the National Lending Library for Science and Technology, Boston Spa, Yorks. LS23 7BQ, U.K., from whom copies can be obtained on the terms indicated in Biochem. J. (1972) 126, 5.     

Localization of albumin, transferrin and alpha-fetoprotein in normal and regenerating mouse liver]

An acetone-formol fixation technique with subsequent paraffin-embedding suitable for immunofluorescent study of different antigens, including serum proteins, is described. This technique was used for detection of albumin, transferrin, and alpha-fetoprotein distribution in the normal and regenerating liver of mice. Albumin and transferrin were always found together in the same hepatocytes, both under normal conditions and in regeneration. In the regenerating liver alpha-fetoprotein was encountered independently of the two other proteins, although it was revealed in the same zones. Only in the perinecrotic zone did each alpha-fetoprotein-positive hepatocyte contain albumin and transferrin.     

The relative affinity of transferrin and albumin for zinc

The relative affinity of transferrin and albumin for zinc has been measured by competitive dialysis at a low zinc concentration in 0.15 M NaCl, 50 mM HEPES, 0.1 mM trisodium citrate (pH 7.2). There were small differences between albumins and larger ones between transferrin preparations, but all albumins bound zinc more firmly than any transferrin did. It is known that transferrin is largely responsible for the uptake of zinc from an intestinal membrane in rats, but much of the metal is subsequently transferred to albumin. The current results show that both in humans and in rats (a) no special mechanism is needed to provide energy for this transfer, and (b) full equilibration would lead to virtually complete transfer in contrast with what actually occurs in vivo.     

The effect of cortisol on the synthesis of rat plasma albumin, fibrinogen and transferrin

A decrease of absolute synthesis of albumin, no change in that of fibrinogen and an increased fractional synthesis of transferrin were observed 3h after intraperitoneal administration of a pharmacological dose of 5 mg of cortisol to 220g rats in the post-absorptive state and previously kept on a diet with 40% protein. The concentration in liver of total free amino acids was practically unchanged at this time. Intraperitoneal administration of a mixture of amino acids with the cortisol raised this concentration and was accompanied by an almost complete de-repression of the synthesis of albumin, with no real effect on that of fibrinogen. In considerable contrast, in rats studied at 24h after intraperitoneal administration of cortisol, and who had been fed once in the interim (but who had received no amino acids intraperitoneally), there was a marked increase in the absolute synthesis of albumin and fibrinogen, with an increase in fractional synthesis that was less proportionately but still very significant and which included transferrin. The amino acid concentrations had risen above the supplemented values at 3h but not as much proportionately as the fractional synthesis rates, and of course not as much as the absolute synthesis rates, of albumin and fibrinogen. These time-dependent effects of cortisol suggest to us that our studies resolve the apparently conflicting results of the effect of cortisol on the synthesis of albumin reported by others.