Lysosomal cobalamin accumulation in fibroblasts from a patient with an inborn error of cobalamin metabolism (cblF complementation group): Visualization by electron microscope radioautography

Journal Article · Thu Aug 01 00:00:00 EDT 1991 · Experimental Cell Research; (United States)

DOI:https://doi.org/10.1016/0014-4827(91)90376-6· OSTI ID:5268870

Vassiliadis, A; Rosenblatt, D S; Cooper, B A; Bergeron, J J.M. ^[1]

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1. McGill Univ., Montreal, Quebec (Canada)

Cobalamin (Cbl, vitamin B{sub 12}) bound to transcobalamin II (TCII) enters cultured fibroblasts by receptor-mediated endocytosis. Following degradation of the TCII, Cbl is subsequently found in either the cytoplasm bound to methionine synthase or in the mitochondria bound to methylmalonyl CoA mutase. In fibroblasts from patients belonging to the cblF complementation group, Cbl is found free in the cell and is not transferred to the above two target enzymes. Quantitative Em radioautography was utilized to visualize intracellular Cbl in fibroblasts from cblF patients and from normal subjects. In cblF cells, 60% of all silver grains were assigned to lysosomes, with only 12.6% over cytoplasm and 1.2% over mitochondria. Subcellular fractionation showed that in cblF cells, the majority of label was associated with clearly recognizable lysosomes. These studies conclusively demonstrate that secondary lysosomes accumulate Cbl in cblF disease.

• OSTI ID: 5268870
• Journal Information: Experimental Cell Research; (United States), Vol. 195:2; ISSN 0014-4827
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
FIBROBLASTS
AUTORADIOGRAPHY
HEREDITARY DISEASES
MOLECULAR BIOLOGY
VITAMIN B-12
SUBCELLULAR DISTRIBUTION
COBALT 57
LYSOSOMES
MITOCHONDRIA
PATIENTS
TRANSMISSION ELECTRON MICROSCOPY
ANIMAL CELLS
BETA DECAY RADIOISOTOPES
CELL CONSTITUENTS
COBALT ISOTOPES
CONNECTIVE TISSUE CELLS
DAYS LIVING RADIOISOTOPES
DISEASES
DISTRIBUTION
DRUGS
ELECTRON CAPTURE RADIOISOTOPES
ELECTRON MICROSCOPY
HEMATINICS
HEMATOLOGIC AGENTS
INTERMEDIATE MASS NUCLEI
ISOTOPES
MICROSCOPY
NUCLEI
ODD-EVEN NUCLEI
RADIOISOTOPES
SOMATIC CELLS
VITAMIN B GROUP
VITAMINS
550301* - Cytology- Tracer Techniques