Synthesis and assembly of membrane skeletal proteins in mammalian red cell precursors

Journal Article · Tue Sep 01 04:00:00 EDT 1987 · J. Cell Biol.; (United States)

DOI:https://doi.org/10.1083/jcb.105.3.1417· OSTI ID:5727679

Hanspal, M; Palek, J

The synthesis of membrane skeletal proteins in avian nucleated red cells has been the subject of extensive investigation, whereas little is known about skeletal protein synthesis in bone marrow erythroblasts and peripheral blood reticulocytes in mammals. To address this question, we have isolated nucleated red cell precursors and reticulocytes from spleens and from the peripheral blood, respectively, of rats with phenylhydrazine-induced hemolytic anemia and pulse-labeled them with (/sup 35/S)methionine. Pulse-labeling of nucleated red cell precursors shows that the newly synthesized alpha- and beta-spectrins are present in the cytosol, with a severalfold excess of alpha-spectrin over beta-spectrin. However, in the membrane-skeletal fraction, newly synthesized alpha- and beta-spectrins are assembled in stoichiometric amounts, suggesting that the association of alpha-spectrin with the membrane skeleton may- be rate-limited by the amount of beta-spectrin synthesized, as has been shown recently in avian erythroid cells. Pulse-chase experiments in the rat nucleated red cell precursors show that the newly synthesized alpha- and beta-spectrin of the cytosol turn over coordinately and extremely rapidly. In contrast, in the membrane-skeletal fraction, the newly synthesized polypeptides of spectrin are stable. In contrast to nucleated erythroid cells, in reticulocytes the synthesis of alpha- and beta-spectrins is markedly diminished compared with the synthesis and assembly of proteins comigrating with bands 2.1 and 4.1 on SDS gels. Thus, in nucleated red cell precursors, the newly synthesized spectrin may be attached to the plasma membrane before proteins 2.1 and 4.1 are completely synthesized and incorporated in the membrane.

• Research Organization: Tufts University School of Medicine, MA
• OSTI ID: 5727679
• Journal Information: J. Cell Biol.; (United States), Journal Name: J. Cell Biol.; (United States) Vol. 105:3; ISSN JCLBA
• Country of Publication: United States
• Language: English

Related Subjects

550201* -- Biochemistry-- Tracer Techniques
59 BASIC BIOLOGICAL SCIENCES
AMINO ACIDS
ANIMALS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
BIOLOGICAL MATERIALS
BIOSYNTHESIS
BLOOD
BLOOD CELLS
BODY
BODY FLUIDS
CARBOXYLIC ACIDS
DAYS LIVING RADIOISOTOPES
DRUGS
ERYTHROCYTES
EVEN-ODD NUCLEI
ISOTOPE APPLICATIONS
ISOTOPES
LIGHT NUCLEI
LIPOTROPIC FACTORS
MAMMALS
MATERIALS
MEMBRANE PROTEINS
METHIONINE
NUCLEI
ORGANIC ACIDS
ORGANIC COMPOUNDS
ORGANIC SULFUR COMPOUNDS
ORGANS
PRECURSOR
PROTEINS
RADIOISOTOPES
RATS
RETICULOCYTES
RODENTS
SKELETON
SPLEEN
SULFUR 35
SULFUR ISOTOPES
SYNTHESIS
TRACER TECHNIQUES
VERTEBRATES