G proteins are so-called because they bind the guanine nucleotides GDP and GTP. They are heterotrimers (i.e., made of three different subunits) associated with. the inner surface of the plasma membrane and. transmembrane receptors of hormones, etc. These are called G protein-coupled receptors (GPCRs).
Apply the metal paint to the mailbox in slow and even sections. Be sure to cover every inch of the metal mailbox including the door, hanging lip and the back. When this layer is dry remove the tape from the mailbox flag.
For pointed pen calligraphy, characterised by graceful curves and strong contrasts in line width, I would recommend trying Nikko G nibs. You can use these in either a traditional or an oblique pen holder, it is a matter of personal preference. Iron Gall ink is best for this type of calligraphy.