KCBP interacts with the cytoskeleton and alters motility in elongating conifer pollen tubes.
Conifer pollen tubes are an interesting model system to study polarized cell growth. Microtubules Microtubules
Slender, elongated anatomical channels in worms.
Mentioned in: Antihelminthic Drugs and microfilaments microfilaments,
n.pl any of the submicroscopic cellular filaments, such as the tonofibrils, found in the cytoplasm of most cells, that function primarily as a supportive system. coordinate to control a unique fountain pattern of organelle organelle /or·ga·nelle/ (or?gah-nel´) a specialized structure of a cell, such as a mitochondrion, Golgi complex, lysosome, endoplasmic reticulum, ribosome, centriole, chloroplast, cilium, or flagellum. streaming within the elongating cell tip. A kinesin like calmodulin calmodulin /cal·mod·u·lin/ (kal-mod´u-lin) a calcium-binding protein present in all nucleated cells; it mediates a variety of cellular reponses to calcium.
n. binding protein (KCBP) is a unique microtubule microtubule
Tubular structure enclosed by a membrane found within animal and plant cells. Of varying length, they have several functions. They help give shape to many cells and are major components of cilia and flagella, participate in the formation of the spindle during motor protein originally discovered in flowering plants that contains two microtubule-binding sites, myosin tail homology, and a regulatory calcium/ calmodulin-binding domain. We are studying KCBP in the conifer pollen tube system of Norway spruce as a potential calcium regulated link between microfilaments and microtubules. We identified a 120 kD KCBP homolog in immunoblots of extracted spruce pollen tube proteins. Using immunofluorescence microscopy, we found that KCBP co localizes with microtubules and microfilaments in the pollen tube tip. We microinjected antibodies that displace calmodulin and activate KCBP into actively growing pollen tubes and found that organelle motility motility /mo·til·i·ty/ (mo-til´ite) the ability to move spontaneously.mo´tile
Motility is spontaneous movement. immediately stops after KCBP activation. We propose that activated KCBP induces microtubule reorganization, leading to the cessation of motility. We are currently probing the calcium dependent calmodulin regulation of KCBP by examining cell elongation and organelle motility while perfusing several compounds across elongating pollen tubes that alter calmodulin activity and that alter cytoplasmic calcium levels by affecting cyclic AMP regulation in the cell. This work was supported by the Deparment of Biology and the Office of Undergraduate Research and Creative Activities at the College of Charleston.