Chemistry of Life

Molecular genetics, biochemistry

proteins

Proteins are complex, macromolecules comprised of amino acids linked by peptide bonds into long chains. The sequence (primary structure) and properties of constituent amino acids generate the 3D conformational structure (tertiary and quaternary structure) that is vital to the biological function of proteins. (click to enlarge image)

Proteins are essential to the structure and biological viability of all living cells and viruses. The cellular proteome is the total cellular protein under a particular set of conditions, while the complete proteome is the sum of all potential proteomes of a cell. Proteomics has become the subject of much research in cell and molecular biology.

Proteins play a number of vital roles as:
a. Enzymes or subunits of enzymes – catalyzing cellular reactions.
b. Structural or mechanical roles – structural components of tissues, components of the cytoskeleton, centrioles, cilia and flagella, microtubules, molecular motors.
c. Intracellular and intercellular signalling functions – ion channels, receptors, membrane pumps.
d. Regulatory proteins in genetic transcription, RNA processing, spliceosomes.
e. Products of immune response that aid in targetting of foreign substances and organisms.
f. Storage and transport of various ligands.
g. The source of essential amino acids.

Almost all natural proteins are encoded by DNA, which is transcribed and processed to yield mRNA, which then serves as a template for translation by ribosomes on the rough endoplasmic reticulum.

Specific proteins/types : cAMP receptor binding protein : cofactor : core histones H2A, H2B, H3, and H4 : CRE-binding protein CREB : elongation factor EF : helicases : Helicase II : heterochromatin : histone : HP1 : inducible transcription factors : LexA repressor : mCAT2 receptor : motor proteins : nucleosome : PcG proteins : PCNA : Polycomb group : proteome : RecA : regulatory proteins : repressor proteins : ribosomes : RPA : serine rich (SR) splicing factors : silencers : Ski7p : small nuclear ribonucleoproteins (snRNPs) : spliceosome : SR (serine rich) splicing factors : trans-acting factors : trithorax group (trxG) : UPF1 UPF2 : upstream transcription factors :

Enzymes : AP endonuclease (Ape1) : DNA glycosylase : DNA Ligase I : DNA polymerases : DNA polymerase I : DNA polymerase beta : DNase IV : exonuclease 1 : exosome : Fen1 : Flap Endonuclease FEN-1 : general transcription factors : hOGG1 : hOGG1 oxoG repair : LigIII : MAP kinase : Msh2-Msh3 : MutS, MutL, and MutH : 8-oxoguanine glycosylase : oxoG repair hOGG1 : PCNA : RNA polymerase: Replication factor C : reverse transcriptase : ribozymes : RNA polymerase II : spliceosomal-mediated RNA trans-splicing SMaRT : trans-splicing ribozymes : UvrD : XRCC1 :

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. . . transcription begun 10/06/06