The Complex Proteome Flashcards
What is the proteome?
The full number of proteins expressed by our DNA
How many protein encoding genes do we have? How does protein regulation affect this number?
20000-25000
Protein regulaiton can contribute to over 1 million proteins due to post translational modifications
mRNA is transcribed in the ____, prepared and exported to the _____, and translated by ____ or ______ _________ into _____________
Nucleus, cytosol, free or ER bound, polypeptides
What are the 4 steps of a cell detecting a signal in order?
Stimulus, Sensor, Effector, Response
What is the stimulus after consuming glucose?
An increase in blood sugar levels
What is the sensor when glucose is consumed?
Regulation from Beta islet cells in the pancreas
What is the effector after glucose is consumed?
Insulin secreted by pancreas cells decreases blood glucose
How does insulin result in a decrease in blood glucose
Body cells take up glucose, liver and muscle cells store glucose as glycogen
What is the response when glucose is consumed?
Glucose absorption decreases blood glucose
Where does most glucose absorption happen?
Some in the mouth, most due to microvilli in the small intestines
Glucose metabolism leads to an ____ in ______ gene transcription and translation
Increase, insulin
Where is insulin produced in the cell?
The rough endoplasmic reticulum (because it is secreted)
What 2 amino acid chains make up insulin?
An alpha chain and a beta chain
What does the insulin gene code for?
A 110 amino acid precursor of the mature insulin protein called preproinsulin
What is the function of the n-terminal sequence of preproinsulin?
Interacts with SRPs for transfer into the ER lumen
The cleavage of the _____ __________ of preproinsulin yields ___________
signal sequence, proinsulin
How is proinsulin modified by post-translation modification?
-Folding in the ER using chaperones
-Cleavage in the GA forming the mature insulin dimer (A and B chains) and releasing a C chain
-Formation of 3 disulfide bonds
What is phosphorylation?
Reversible modification involving covalent attachment of phosphate to serine, threonine, or tyrosine by kinase enzymes
Where does insulin go when released?
Bind to receptors called kinases on target tissues, allowing glucose to be taken into the cytosol
What are receptors?
Receptors recieve and interpret information from signalling molecules
Receptor kinases exist in ______ forms and when insulin binds, they ________
mononeric, dimerize
What happens when receptor kinases dimerize?
-phosphorylation of specific amino acids, and the
-binding and activation of cytoplasmic proteins
-Activation of glucose transporter proteins at the cell membrane
_______ cells absorb glucose more efficiently than ____ cells
skeletal muscle, liver
What is alternative splicing of pre-mRNA?
Allows pre-mRNA to be spliced at different junctions to create many different mRNA molecules with different exon combinations
What is different about insulin receptors in skeletal muscle cells?
Exon 2 is removed during processing, translating a higher affinity version so the cells can have greater glucose uptake
