M protein

M protein may refer to:

• M protein (Streptococcus), a virulence factor of the bacterium Streptococcus pyogenes
• Another name for viral matrix protein, non structural protein linking the viral envelope with the virus capsid
• Myeloma protein, also called paraprotein, an abnormal protein in the urine or blood, often seen in multiple myeloma or MGUS
• Myomesin-2 (MYOM2), a protein composing the M-line of muscle cell sarcomeres.
• Protein M in Mycoplasma genitalium which is different from the above mentioned M protein