Protein of the Day #3: Bone morphogenic protein 7

In this week's Nature there is some exciting news about what makes brown adipose tissue, or "brown fat". It turns out that brown fat actually comes from muscle precursor cells, not fat cells, and bone morphogenic protein 7 (Bmp7) can induce the transformation.

Brown fat is very important in hibernation as it can generate heat by short-circuiting the mitochondrial proton pump. At very low temperatures, animals cannot shiver so they need other heat generating mechanisms. Its also important for infant mammals, including humans.

Bmp7 is part of the TGF-beta superfamily (transforming growth factors). In the human its on chromosome 20. 7 exons, very typical gene in that respect.

Brown fat has generated a lot of controversy over the years (since 1551!); this discovery seems like a big step forward.

Protein of the Day #2: Clathrin

Clathrin is a very cool protein. It forms polyhedral lattices that help cells in endocytosis. Your synapses are using a lot of clathrin right now.

Protein of the Day #1: Alpha-2 Macroglobulin

Long time no post. I've decided to try a "Protein of the Day" post mostly to help myself remember some of them.

For protein #1, I've picked alpha-2 macroglobulin, a serum protease inhibitor. NCBI's Online Mendelian Inheritance in Man (OMIM) is a nice curated resource for protein/gene information and its where I often turn first. Wikipedia has a nice entry too - the quality of wikipedia articles in biochemistry is usually excellent in my experience so far.

Its a glycoprotein, so there are some extra carbohydrates attached. There are four subunits held together by SS bonds. The gene structure is relatively complicated, with 36 exons (same number in human and mouse. It is thought to be evolutionarily related to the C3 and C4 proteins.

My interest in it mainly stems from the fact that it is important in mammalian hibernation. Among many other effects, it inhibits coagulation and fibrinolysis.