ISSN:
0002-9106
Schlagwort(e):
Life and Medical Sciences
;
Cell & Developmental Biology
Quelle:
Wiley InterScience Backfile Collection 1832-2000
Thema:
Medizin
Notizen:
The distribution and behavior of anionic sites on the micro-villous surface of rat jejunal absorptive cells were studied using the multivalent ligand polycationic ferritin (PCF) as a visual probe. Segments were incubated in PCF either before or after glutaraldehyde fixation. The results indicated that the anionic sites can be divided into three groups based on their interaction with PCF: (1) Some sites along the length of the microvilli are accessible for binding PCF in living, unfixed cells. These sites are capable of translational mobility at the membrane surface and can be induced to cluster into discrete patches by PCF. Under appropriate conditions, they may be taken into the cell by endocytosis. Their redistribution is prevented by prefixation, and slowed by incubation at temperatures of 0°C or below. (2) Some sites along the length of the microvilli are inaccessible to PCF without prior fixation. These sites may provide uniform coverage or may be preferentially localized to the distal microvillus. (3) Some sites restricted to the microvillous tips are accessible to PCF without fixation, but are apparently immobile. Their high density on some tips forms a distinctive cap of ferritin particles. More anionic sites were found on the microvilli of the more mature cells of the upper villus. In addition, independent variation was observed in the number of sites in each of the three groups among neighboring cells, irrespective of villous position, suggestive of variations in the turnover of these sites.
Zusätzliches Material:
1 Ill.
Materialart:
Digitale Medien
URL:
http://dx.doi.org/10.1002/aja.1001520303
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