You are examining the behavior of two centrosomal proteins C

You are examining the behavior of two centrosomal proteins Centrin and Cep 192 by FRAP analysis. Both proteins are expressed as GFP-tagged for ms, which localize to the centrosome (Centrosome is indicated by red arrow). p.b. is before bleaching, the subsequent images show time points during recovery from photo bleaching (time s indicated in minutes and the time course shows the fluorescent signal at the centrosome over time, always focusing on the centrosome). Which of the following conclusions con you draw from this experiment? The legend to this figure (taken from a research paper by Zhu et al., 2008. Current Biology 18, 136-141) Both, Centrin and Cep 192 are stably associated with the centrosome and do not exchange with cytosolic subunits. Centrino-GFP deploys a mere dynamic behavior than Cep 192 Cep192-GFP is more dynamic than Centrino This experiment travels that centrosome application depends on Cep 192 This experiment travels that centrosome duplication depends on Contain What do you expect to see if you fixed the cells from question 12 (after the FRAP experiment has been performed) and stained for centric and Cep 192 by immunofluorescence with specific antibodies to those proteins, followed by staining with appropriate secondary antibodies? Centrino and Cep 192 will be absent from the centrosome Centrino will be absent but Ceil 192 will be present at the centrosome Contain and Cep 192 will both be present at the centrosome

Solution

Centrosome is a microtubule organizing center in mammalian cell. Biploar mitotic spindle assembly depend on centriole duplication and maturation. Regulation of this 2 processes is require for proper cell division. In this process Cep 192 is a major regulator of centrosome maturation and centriole duplication in cells.

In this experiment, FRAP analysis perform to examine protein dynamics. In this experiment, proteins are tagged with GFP and then observed at different time point after bleaching. Presence of flourescence after bleaching proves that flourescence of region recover when unbleached GFP tagged protein from outside of the region diffuses into the region of interest. Here, result clearly represent presence of flourescence after bleaching in Cep192 then centrin, So, this experiment conclude that Cep192 is more dynamic then centrin. Answer is option C. Cep192 is in dynamic equilibrium with its cytoplasmic pool whereas centrin stably associated centriolar protein.

The next answer is C. Both centrin and cep 192 present at the centrosome in fixed cells. Cep 192 prefrentially surrounded one of the two centrin positive structure per pole. Both the protein present in the centrosome.