FORM 4
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Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

UNITED STATES SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549

STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP

Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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1. Name and Address of Reporting Person *
SEIDENBERG BETH C
 2. Issuer Name and Ticker or Trading Symbol
Atara Biotherapeutics, Inc. [ATRA] 		5. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director _____ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
(Last)
(First)
(Middle)

C/O ATARA BIOTHERAPEUTICS, INC., 2380 CONEJO SPECTRUM ST, SUITE 200		 3. Date of Earliest Transaction (Month/Day/Year)
05/31/2023
(Street)

THOUSAND OAKS, CA 91320
(City)
(State)
(Zip)
4. If Amendment, Date Original Filed(Month/Day/Year)
6. Individual or Joint/Group Filing
(Check applicable line)

__X__ Form Filed by One Reporting Person
_____ Form Filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned

1.Title of Security (Instr. 3)

2. Transaction Date (Month/Day/Year)

2A. Deemed Execution Date, if any (Month/Day/Year)

3. Transaction Code (Instr. 8)

4. Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)

5. Amount of Securities Beneficially Owned Following Reported Transaction(s)
(Instr. 3 and 4)

6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)

7. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

Amount

(A) or (D)

Price

Common Stock

05/31/2023 A 57,000 (1) A $ 0 115,689D 

Common Stock

       1,822,228I

See footnote (3)

Common Stock

       54,422I

See footnote (4)

Common Stock

       197I

See footnote (5)

Common Stock

       197I

See footnote (6)



Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned
(e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security
(Instr. 3)

2. Conversion or Exercise Price of Derivative Security

3. Transaction Date (Month/Day/Year)

3A. Deemed Execution Date, if any (Month/Day/Year)

4. Transaction Code
(Instr. 8)

5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4, and 5)

6. Date Exercisable and Expiration Date (Month/Day/Year)

7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)

8. Price of Derivative Security (Instr. 5)

9. Number of Derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)

10. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 4)

11. Nature of Indirect Beneficial Ownership (Instr. 4)

Code

V

(A)

(D)

Date Exercisable

Expiration Date

Title

Amount or Number of Shares

Non-Qualified Stock Option (Right to Buy)

 $1.5305/31/2023 A 79,500   (2) 05/30/2033

Common Stock

79,500 $ 0 79,500D 

Explanation of Responses:
1.

These restricted stock units shall vest on the earlier of May 31, 2024 or the date of the next annual meeting of stockholders, subject to the Reporting Person's continuous service.

2.

The option shall vest on the earlier of May 31, 2024 or the date of the next annual meeting of stockholders, subject to the Reporting Person's continuous service.

3.

The shares are directly held by Kleiner Perkins Caufield & Byers XV, LLC ("KPCB XV"). All shares are held for convenience in the name of "KPCB Holdings, Inc., as nominee". The managing member of KPCB XV is KPCB XV Associates, LLC ("XV Associates"). The voting and dispositive control over the shares is shared by individual managing members of XV Associates, none of whom has veto power.

4.

The shares are directly held by KPCB XV Founders Fund, LLC ("KPCB XV FF"). All shares are held for convenience in the name of "KPCB Holdings, Inc., as nominee". The managing member of KPCB XV FF is XV Associates. The voting and dispositive control over the shares is shared by individual managing members of XV Associates, none of whom has veto power.

5.

Shares held by the Michael J. Seidenberg Irrevocable Trust, established July 1, 2013, of which the Reporting Person is a trustee.

6.

Shares held by the Samuel B. Seidenberg Irrevocable Trust, established July 1, 2013, of which the Reporting Person is a trustee.

Remarks:

Exhibit List: Exhibit 24 - Power of Attorney



Signatures

/s/ Jeff Kiekhofer, Attorney-in-Fact

06/02/2023
** Signature of Reporting PersonDate
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (b)(v).
** Intentional misstatements or omissions of facts constitute Federal Criminal Violations See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
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Exhibit 24

POWER OF ATTORNEY

The undersigned, as a Section 16 reporting person of Atara Biotherapeutics, Inc. (the "Company"), hereby constitutes and appoints Utpal Koppikar, David Tucker, Jeff Kiekhofer, Amar Murugan, John Chao and Kathleen Klaben the undersigned's true and lawful attorneys-in-fact to:

1.        Complete and execute Forms 3, 4 and 5 and other forms and all amendments thereto as such attorneys-in-fact shall in their discretion determine to be required or advisable pursuant to Section 16 of the Securities Exchange Act of 1934 (as amended) and the rules and regulations promulgated thereunder, or any successor laws and regulations, as a consequence of the undersigned's ownership, acquisition or disposition of securities of the Company; and

2.        Do all acts necessary in order to file such forms with the Securities and Exchange Commission, any securities exchange or national association, the Company and such other person or agency as the attorneys-in-fact shall deem appropriate.

The undersigned hereby ratifies and confirms all that said attorneys-in-fact and agents shall do or cause to be done by virtue hereof. The undersigned acknowledges that the foregoing attorneys-in-fact, in serving in such capacity at the request of the undersigned, is not assuming, nor is the Company assuming, any of the undersigned's responsibilities to comply with Section 16 of the Securities Exchange Act of 1934 (as amended).

This Power of Attorney shall remain in full force and effect until the undersigned is no longer required to file Forms 3, 4 and 5 with respect to the undersigned's holdings of and transactions in securities issued by the Company, unless earlier revoked by the undersigned in a signed writing delivered to the Company and the foregoing attorneys-in-fact.

The undersigned hereby terminates all prior powers of attorney regarding the subject matter hereof.

IN WITNESS WHEREOF, the undersigned has caused this Power of Attorney to be executed as of June 2, 2022.

 
Signature:
/s/ Beth Seidenberg
   
Beth Seidenberg, M.D.