Nascent-polypeptide-associated complex alpha polypeptide, also known as NACA, is a

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, respo ...

which in humans is encoded by the ''NACA''

gene In biology, the word gene (from , ; "...Wilhelm Johannsen coined the word gene to describe the Mendelian units of heredity..." meaning ''generation'' or ''birth'' or ''gender'') can have several different meanings. The Mendelian gene is a ba ...

Function

NACA prevents short recently synthesized (i.e., nascent)

ribosome Ribosomes ( ) are macromolecular machines, found within all cells, that perform biological protein synthesis (mRNA translation). Ribosomes link amino acids together in the order specified by the codons of messenger RNA (mRNA) molecules to ...

-associated polypeptides from inappropriate interactions with cytosolic proteins. NACA binds nascent-polypeptide domains emerging from ribosomes unless it contains a

signal peptide A signal peptide (sometimes referred to as signal sequence, targeting signal, localization signal, localization sequence, transit peptide, leader sequence or leader peptide) is a short peptide (usually 16-30 amino acids long) present at the N-ter ...

which is fully exposed. Depletion of NACA from ribosomes carrying nascent polypeptides allows the

signal recognition particle The signal recognition particle (SRP) is an abundant, cytosolic, universally conserved ribonucleoprotein (protein-RNA complex) that recognizes and targets specific proteins to the endoplasmic reticulum in eukaryotes and the plasma membrane ...

(SRP) to crosslink to polypeptides regardless of whether or not they contain signal peptides or not. In the absence of NACA, proteins lacking signal peptides can be mis- translocated into the

endoplasmic reticulum The endoplasmic reticulum (ER) is, in essence, the transportation system of the eukaryotic cell, and has many other important functions such as protein folding. It is a type of organelle made up of two subunits – rough endoplasmic reticulum ( ...

. The NACA protein is expressed in bone during development and acts as a transcriptional coactivator in conjunction with acidic activators.

Interactions

NACA has been shown to

interact Advocates for Informed Choice, dba interACT or interACT Advocates for Intersex Youth, is a 501(c)(3) nonprofit organization using innovative strategies to advocate for the legal and human rights of children with intersex traits. The organizati ...

with

BTF3 Transcription factor BTF3 is a protein that in humans is encoded by the ''BTF3'' gene. Function This gene encodes the basic transcription factor 3. This protein forms a stable complex with RNA polymerase IIB and is required for transcriptional ...

FADD FAS-associated death domain protein, also called MORT1, is encoded by the ''FADD'' gene on the 11q13.3 region of chromosome 11 in humans. FADD is an adaptor protein that bridges members of the tumor necrosis factor receptor superfamily, such a ...

C-jun Transcription factor Jun is a protein that in humans is encoded by the ''JUN'' gene. c-Jun, in combination with protein c-Fos, forms the AP-1 early response transcription factor. It was first identified as the Fos-binding protein p39 and only lat ...

, and 3 members of taxilin family.

Function

Interactions

References

Further reading