The human genome encodes approximately 5000 membrane-embedded proteins that carry out many essential processes such as cell-to-cell communication, cell adhesion and intracellular trafficking. Almost all of these proteins are assembled at the endoplasmic reticulum (ER) by molecular machines that guide them into the membrane. Because these thousands of membrane proteins are highly diverse in size, shape and charge, different machines are needed for different types of membrane proteins.
All the cells in our body contain thousands of proteins, molecular machines which carry out almost all biological processes that are essential for life. Many diseases, such as cancer and neurodegeneration, are caused when these protein machines go wrong. Thus it has been a long-term goal in science to characterise the functions of proteins within our cells.
The spliceosome is a molecular machine that plays an important role in gene expression. It cuts non-coding sequences (introns) out of messenger RNA (mRNA) precursors, and stitches together the useful coding sequences (exons). The spliceosome performs this in two steps. First, the start of an intron is recognised, cut, and joined to a specific point in the middle of that intron, forming a lasso-like looped structure.
Internal body clocks, which time the length of a day in almost all organisms, control many aspects of human physiology and activity, from when we go to bed to when we perform best mentally and physically. Most importantly, these biological circadian clocks are in every single individual cell of our bodies, not just in the brain.
Parkinson’s disease (PD) is a neurodegenerative condition caused by the loss of dopaminergic neurons in the midbrain, which manifests clinically in the form of characteristic motor defects. Most PD cases are sporadic and found in people above the age of 60. However, roughly 10% of PD cases are autosomal recessive juvenile forms (AR-JP), causing early-onset PD. It is known that mutations in PARK genes are responsible for this, but often a molecular explanation is lacking.
Inside our cells there are many distinct membrane compartments – organelles – which carry out the different tasks that allow the cell to function. Each organelle is like a factory that requires a constant supply of raw materials to stay active. Small transport vesicles deliver this cargo of particular proteins and lipids to each organelle.