Cat2p catalyzes the reversible transfer of acetyl groups between acetyl-CoA and L-carnitine, generating acetylcarnitine as a membrane-permeant carrier of acetyl units; in the peroxisome it forms acetylcarnitine, and in mitochondria the reverse reaction regenerates acetyl-CoA for the TCA cycle.

Cat2p is the principal enzymatic component of the yeast carnitine shuttle for acetyl-unit transfer between organelles, operating in parallel with a glyoxylate-cycle (CIT2) route; loss of both systems abolishes growth on oleate.

Cat2p is dually localized to peroxisomes and mitochondria; dual targeting is mediated by two ATG codons producing isoforms, one with an N-terminal mitochondrial targeting signal and a C-terminal PTS1 providing peroxisomal targeting.

In S. cerevisiae only carnitine acetyltransferase activity has been described; yeast lacks long-chain carnitine acyltransferase activity, so Cat2 acts on acetyl-CoA/acetylcarnitine rather than long-chain acylcarnitines.

Cat2p provides the majority of total carnitine acetyltransferase activity in yeast (~95% in oleate-grown cells; >99% in galactose-grown cells).

A 2024 integrative omics study reports Cat2 localization is sensitive to tag placement: an N-terminal fluorescent tag showed punctate/peroxisomal localization, whereas C-terminal tagging disrupted the PTS1-dependent punctate pattern, yielding predominant mitochondrial localization.