Canadian Advanced Nanospace eXperiment Program

The Canadian Advanced Nanospace eXperiment (CanX) program is a Canadian CubeSat nanosatellite program operated by the University of Toronto Institute for Aerospace Studies, Space Flight Laboratory (UTIAS/SFL). The program's objectives are to involve graduate students in the process of spaceflight development, and to provide low-cost access to space for scientific research and the testing of nanoscale devices. The CanX projects include CanX-1, CanX-2, the BRIght Target Explorer (BRITE), and CanX-4&5.

The CanX Program

The Canadian Advanced Nanospace eXperiment (CanX) program is the first Canadian nanosatellite program, and the only one of its kind at present. It is operated by teachers and graduate students at the University of Toronto Institute for Aerospace Studies, Space Flight Laboratory (UTIAS/SFL). The program was established in 2001 by Dr. Robert E. Zee, manager of UTIAS/SFL, and is based on the CubeSat program started by Stanford University and California Polytechnic State University. Its projects include CanX-1, CanX-2, CanX-3 (BRITE), and CanX-4&5.

BRITE

Bright Target Explorer or BRITE, also known as Canadian Advanced Nanospace eXperiment 3 (CanX-3) is a constellation of six nanosatellites operated by a consortium of universities from Canada, Austria and Poland.

The BRITE satellites were designed by the Institute for Aerospace Studies at the University of Toronto under the Canadian Advanced Nanospace eXperiment Program. The satellites is built around the Generic Nanosatellite Bus, a cube-shaped spacecraft with sides of 20 centimetres (7.9 in) which was first used in current BRITE version for the satellite CanX-3. One satellite is called BRITE-Toronto while the other is called BRITE-Montreal.

BRITE Constellation was included in the #7 entry in the Top Ten Science Stories of 2013, as chosen by Bob McDonald, host of the Canadian Broadcasting Corporation (CBC) radio show Quirks&Quarks, and the main science journalist for CBC radio and television.

Launches

Mission

The satellite is intended for astro-photometry of the brightest stars in single wavelength band. UniBRITE-1, BRITE-Toronto and Heweliusz BRITE-PL photometers are sensitive to the red light, while BRITE-Montreal, Lem BRITE-PL and BRITE-AUSTRIA are sensitive to the blue light.

Calnexin

Calnexin (CNX) is a 67kDa integral protein (that appears variously as a 90kDa, 80kDa or 75kDa band on western blotting depending on the source of the antibody) of the endoplasmic reticulum (ER). It consists of a large (50 kDa) N-terminal calcium-binding lumenal domain, a single transmembrane helix and a short (90 residues), acidic cytoplasmic tail.

Function

Calnexin is a chaperone, characterized by assisting protein folding and quality control, ensuring that only properly folded and assembled proteins proceed further along the secretory pathway. It specifically acts to retain unfolded or unassembled N-linked glycoproteins in the ER. Calnexin binds only those N-glycoproteins that have GlcNAc2Man9Glc1 oligosaccharides. These monoglucosylated oligosaccharides result from the trimming of two glucose residues by the sequential action of two glucosidases, I and II. Glucosidase II can also remove the third and last glucose residue. If the glycoprotein is not properly folded, an enzyme called UGGT (for UDP-glucose:glycoprotein glucosyltransferase) will add the glucose residue back onto the oligosaccharide thus regenerating the glycoprotein's ability to bind to calnexin. The improperly-folded glycoprotein chain thus loiters in the ER, risking the encounter with MNS1 (alpha-mannosidase), which eventually sentences the underperforming glycoprotein to degradation by removing one of the nine mannose residues. If the protein is correctly translated, the chance of it being correctly folded before it encounters MNS1 is high.