What does '*' Amino Acid in BLOSUM Matrix of MATLAB mean?

Question

[mithrandir]

The BLOSUM(n) [e.g. BLOSUM(62)] returns a 24 by 24 matrix with the following amino acid sequence 'A R N D C Q E G H I L K M F P S T W Y V B Z X *'. The first 20 are amino acids, the next three are special amino acid characters, what does * stand for? Does it stand for Gap(-). Source: http://in.mathworks.com/help/bioinfo/ref/blosum.html

Answer 1

[Aerval]

Its a translation stop. See here or here. Btw, I also just googled ;)

Answer 2

[Michael]

Wherever I have seen it * stands for stop-codon.