ABSTRACI Young chickens were administered L-[SH]leucine and after 10 or 30 min the livers were removed and fractionated into rough (RER) and smooth (SER) endoplasmic reticulum fractions and into light, intermediate, and heavy Golgi cell fractions. The labeled high density lipoprotein (HDL), contained within these intracellular organelles was isolated either by immunoprecipitation using rabbit antiserum to rooster HDL, or by ultracentrifugal flotation between densities 1.063 and 1.21 g/ml. The radioactive apoproteins of nascent HDL were analyzed by SDS PAGE and detected by fluorography. Analyses of radioactive apoproteins obtained by immunoprecipitation from the contents of the RER, the SER, and the three Golgi complex fractions revealed only one apoprotein, A1. The C peptide present in serum HDL was not detected intracellularly. The radioactive apoprotein A1 which is present within the cisternae of the RER and the SER fractions failed to float, whereas apoprotein A1, present within the Golgi apparatus, readily floated between densities 1.063 and 1.21 g/ml. The HDL particles, isolated by flotation from the Golgi apparatus content, were further characterized by lipid and protein analyses and by electron microscopy. Golgi HDL particles have the same density as serum HDL. On a percentage basis, Golgi HDL contains less protein and more phospholipids than does serum HDL. Morphologically, Golgi HDL is different in appearance from serum HDL. It is more heterogeneous in size, with most of the particles ranging 8.3-25 nm in diameter. The spherical particles contain small membrane tails. Occasionally, a few disk-shaped bilayer structures are also found within the Golgi apparatus. These studies show that the newly synthesized apoprotein A1, present within the RER and the SER cell fractions, is not fully complexed with lipid and that apoprotein A1 does not acquire sufficient lipid to float at the proper HDL density until it enters the Golgi apparatus. The difference in chemical composition and the heterogeneous size of Golgi HDL may be attributed to the different stages of HDL maturation.Plasma lipoproteins are lipid-protein complexes responsible for the transport of lipids in the blood. Four major classes of lipoproteins have been isolated from serum in all species tested and are designated according to their particle size and buoyant density as chylomicron (size: > 100 nm in diameter; d = <0.95 g/ml), very low density lipoprotein (VLDL: 30-80 nm in diameter, d ----0.95-1.006 g/ml), low density lipoproteins (LDL: 28 nm in diameter; d = 1.006-1.063 g/ml) and high density lipoproteins (HDL: 8-12 nm in diameter; d = 1.063-1.21 g/ ml). The distribution, composition, physicochemical properties, and metabolism of HDL have been well studied (7,13,19,28,48), but very little is known about the mechanisms by which HDL is produced.In all species that have been studied, the liver and small intestine are found to be the major sites of HDL production (18,19). HDL is synthesized independently and it is not formed in the blood as a metabol...

McLeod phenotype red cells of the Kell blood group system have acanthocytic morphology and reduced in vivo survival. The phenotype has an X-linked mode of inheritance and is found in some males who have no abnormality of leukocyte function and in some who have X-linked chronic granulomatous disease (CGD). We now describe an association between the McLeod phenotype and an abnormal elevation of serum creatine phosphokinase (CPK). The increase is of the MM isoenzyme type, derived from skeletal muscle or cardiac muscle, and muscle biopsy shows evidence of muscle cell changes. All of 11 males who have McLeod syndrome but do not have CGD have high levels of serum CPK. Males with McLeod syndrome and CGD may have normal or high levels of the enzyme. Individuals with other variant phenotypes in the Kell system have normal levels of serum CPK. Studies on a large kindred, which includes 5 people of McLeod phenotype, show high CPK levels only in the members of McLeod type. We conclude that the high level of CPK in the serum of these people is a reflection of a muscle cell anomaly and that in these individuals it is a pleiotropic effect of the X-linked gene that produces the McLeod red cell phenotype.

The Kell blood group is one of the major antigenic systems in human red blood cells. To determine the location of the Kell gene on human chromosomes, panels containing genomic DNA of human-hamster somatic cell hybrids were hybridized with radiolabeled cDNA probe specific for the Kell locus. Only the samples containing DNA from chromosome 7 gave positive hybridization signals. In situ hybridization analysis, using genomic clones isolated with the cDNA, localized the KEL gene to 7q33. Northern blot analysis of poly(A)+ RNA from human brain, kidney, lung, fetal and adult liver, and bone marrow showed that Kell transcripts were only present in fetal liver and bone marrow. This indicates that the Kell protein, which carries the Kell antigens, may only be expressed in erythroid tissues.